CA1064169A - Process for purification of waste water - Google Patents
Process for purification of waste waterInfo
- Publication number
- CA1064169A CA1064169A CA275,345A CA275345A CA1064169A CA 1064169 A CA1064169 A CA 1064169A CA 275345 A CA275345 A CA 275345A CA 1064169 A CA1064169 A CA 1064169A
- Authority
- CA
- Canada
- Prior art keywords
- reaction zone
- waste water
- fluidized bed
- suspended solids
- solids
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/08—Aerobic processes using moving contact bodies
- C02F3/085—Fluidized beds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/20—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with liquid as a fluidising medium
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1205—Particular type of activated sludge processes
- C02F3/1215—Combinations of activated sludge treatment with precipitation, flocculation, coagulation and separation of phosphates
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/30—Aerobic and anaerobic processes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
A B S T R A C T.
A purification process for removal of suspended solids, carbonaceous material, nitrogenous material, phosphorus, refrac-tory organics, bacteria and viruses comprises of combining and carrying our the various biochemical and chemical reactions and separation of the suspended solids in a single sludge system in a simplified process sequence suitable for use in a single reac-tion tank.
The biooxidation, nitrification, denitrification and chemical predipitation processes are carried out in presence of mixed mi-crobial population entrapped into fluidized nonbiodegadable sus-pended solids with portion of the fluidized suspended solids cir-culating through three reaction zones having varying concentration of disolved oxygen to maintain enviromental conditions to support growth of the microbial population and simultaneously to maintain operating conditions required to carry out the involved reactions.
The fluidized suspended solids entrap the active microorganisms, colloidal matter and suspended solids present in the incoming waste water and/or generated during purification of the waste water, imp-rove the settling properties of the resulting sludge and enhance separation of suspended solids from the purified waste water.
The concentration of the active microbial population in this purification process is significantly higher than that achieved by the prior art processes resulting in better performance, more effi-cient removal of pollutants and reduced treatment costs. The follo-wed chemical oxidation provides for removal of remaining impurities and killing of bacteria and viruses.
A purification process for removal of suspended solids, carbonaceous material, nitrogenous material, phosphorus, refrac-tory organics, bacteria and viruses comprises of combining and carrying our the various biochemical and chemical reactions and separation of the suspended solids in a single sludge system in a simplified process sequence suitable for use in a single reac-tion tank.
The biooxidation, nitrification, denitrification and chemical predipitation processes are carried out in presence of mixed mi-crobial population entrapped into fluidized nonbiodegadable sus-pended solids with portion of the fluidized suspended solids cir-culating through three reaction zones having varying concentration of disolved oxygen to maintain enviromental conditions to support growth of the microbial population and simultaneously to maintain operating conditions required to carry out the involved reactions.
The fluidized suspended solids entrap the active microorganisms, colloidal matter and suspended solids present in the incoming waste water and/or generated during purification of the waste water, imp-rove the settling properties of the resulting sludge and enhance separation of suspended solids from the purified waste water.
The concentration of the active microbial population in this purification process is significantly higher than that achieved by the prior art processes resulting in better performance, more effi-cient removal of pollutants and reduced treatment costs. The follo-wed chemical oxidation provides for removal of remaining impurities and killing of bacteria and viruses.
Description
T I T L E O F I N V E N T I O N
"Prooess for Purification of Sanitary Waters"
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- FIELD OF INVENIION
This invention relates to purification of waste waters, parti-cularly to removal of pollutants such as suspended solids, carbona-ceous material, nitrogenous material, phosphorus, bacteria and vi-ruses present in domestic waste waters.
The prooe ss of this invention utilizes fluidized nonbiodegrad-able suspended solids to increase the concentration of mixed micro-~- bial population in the reaction system to improve the efficiency of biochemical reactions, to improve the efficiency of chemical preci-pitation of phosphorus through more efficient coagulation of the for-med precipitates and through adsorption of phosphorus on the flui-dized suspended solids and to improve the efficiency of separation of suspended solids from the purified wasteswater by coagulation of the solids into large floccs retained in the fluidized bed.
The pracess hydraulics permits better control of the environ-mental conditions required by the microbial population and the si-multaneously occurring bio-oxidation reactions requiring oxygen and denitrification reactions requiring absen oe of oxygen.
BACKGROUND TO THE INVENTION
It has beco~e evident that nitrogen and phosphorus affect the productivity of aquatic life - nitrogen being the limiting nutrient in eutrophic waters and phosphorus in oligotrophic waters.
It is also known that municipal waste waters contain from 10 to 100 times the nutrient concentration of agricultural or forest drainage. Consequently in densely populated areas overfertilization of surfaoe waters, algae growth and chemical pollution have been no-ticed along with degradation of potable water sources and the need for m~re efficient removal of organics, nitrogenous ccmpounds and phosphorus from all waste waters has become more obvious.
While removal of phosphorus can be achieved reliably by chemi-cal precipitation and removal of organics by biological follcwed by physical chemical prooesses, removal of nitrogen is more complicated.
~ q3 m e current processes of ammonia stripping, break ~oint chlo-rination, ion exchange and biological nitrification followed by biological denitrification are relatively oomplex and expensive.
Although conventional activated sludge prooe ss is capable of removing up to 50 - 60 percent of the nitrogen frc~ treated waste waters, the removal of nitrogen is eratic and in most cases it's major part is discharged in mineralized form in the effluent.
The biologieal transformations of nitrogenous compounds occure through biological pro oesses of am~onification, nitrification and denitrification. The first two require presen oe of oxygen, the de-nitrification require absenoe of oxygen. The two distinct mechan-isms responsible for removal of nitrogen and reduction of nitrite and nitrate are (a) - formation of ammonia followed by transfer of ammonia into the anabolic oe ll metabolism which is of minor impor-tanee sinee C:N ratio in eell tissue is 5 - 6, whereas in domestie waste waters only 2- 2.5, and (b) - mierobial denitrification, which is a respiratory reduction is whieh nitrite and nitrate rep-laoe oxygen as the final eleetron acoeptors in the respiration chain.
Considerable number of heterotrophic faeultative and obligate anaerobie baeteria speeies ean transfer eleetrons to nitrite in-stead of oxygen in the respiratory ehain, and all substrates nor-mally used by the eells for respiration may serve as eleetron do-nors for the reduetion proeess regardless of whether they are pre-sent in the external medium, or whether they have to be mobiliz~d from intraoellular assimilates.
m e reduetion of nitrate is eonsidered to be an adaptive pro-perty of those baeteria that ean reduoe nitrite for respiration.
The reduetion meehanism for bio-oxidation of organie matter and for transformation of the nitrogenous ecmpounds is expressed by reactions listed in Table 1.
Bio-oxidation of organie matter, ammonifieation and nitrifiea-tion eause no problems. Nitrifieation is effieient and reliable if organie loadings are maintained below 0.3 lb BOD per lb of mixed liquor suspended solids per day, sludge age is maintained above 3-4 days and dissolved oxygen in the mixed liquor is maintained above 1.0 - 2.0 mg/L. Ihe higher is the concentration of mixed liquor sus-pended solids, the more efficient is the transformation of ammonia to nitrite and nitrate. The overall rate of denitrification is a function of the concentration of the heterotrophic facultative bacteria present in mixed liquor suspended solids and their activity in the absen oe of oxygen. To maintain the activity the denitrifying bacteria must be supplied with suitable organic material - source of energy.
Yrom the process point of view to accomodate the different food and oxygen requirements of bio-oxidation of organic matter, ammoni-fication and nitrification of nitrogenous compounds and decomposi-tion of nitrite and nitrate by the microbial respiration and to achieve acoeptable reaction rates and efficiencies, the various biochemical reactions are currently being carried out in separate pro oess stages.
While the eonventional activated sludge process is capable of remov-ing nitrogen with effieiency of 50 - 60 peroent, the current multi-stage processes ean achieve the removal of nitrogen with efficiency up to 80 - 90 peroent.
The multistage prooesses currently in use in large munieipal treatment plants require treatment facilities that are too eomplex to be scaled dcwn to small package plants to serve small develop-ments or single family dwellings. More, the established biological processes are inefficient in removal of biologically resistant ccm-pounds recognized as refractory organics and the Physical-ehemical treatments are ineffieient in removal of low organic acids and low carbohydrates both highly soluble and present in considerable con-oentrations in domestie and munieipal waste waters. ConsequentLy neither the biological, nor the ehemical - physical treatments alone can effieiently reduce the coneentration of organic contaminants to the level found in fresh waters. The required combination of the bio-logieal and physical - chemical treatments therefore further inerea-ses the complexity of the treatment and the treatment faeilities.
Furthermore, biological pro oesses that utilize low organie loa-dings to achieve low yields generate sludges that have poor coagu-lation properties, requiring low overflow rates in elarifiers and eausing relatively high losses of solids in effluents.
Because of the number of process steps required for removal of the various pollutants renovation and reuse of d estie waste waters at present seems feasible only if praetieed on a large seale.
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A large waste water treatment - renovation plant however requi-res large underground sewage collection - transportationnetwork, and in case the renovated water is reused a large underground water distribution network. Such netwDrks are expensive to build and even 5 more expensive to maintain and to operate.
It is therefore obvious that on-site renovation and reuse of waste water would be economically more attractive than renovation and reuse of waste waters via central collection-treatment-distri-bution. However, because of the camplexity of the involved treat-i 10 ment on-site renovation and reuse of domestic waste water as yet can't be practiced.
Although, at present small package sewage treatment plants are available, they do not provide the required degree of purification that would permit reuse of the purified effluent and in general they 15 also lack the required process stability.
It is therefore the prime object of this invention to reduoe the number of process steps required by the present art and carried out in separate process stages when removing suspended solids, carbona-oeous material, nitrogenous material, phosphorus, bacteria and vi- I
20 ruses fram domestic waste waters and to provide a purification pro-cess having a simple process sequence and capable of rem~ving the various pollutants more-less simultaneously.
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MDre particularly it is the object of this invention to provide a process for purification of sanitary waters and purification of 25 some industrial waste waters, which would be capable of achieving reliable and efficient removal of suspended solids, bio-oxidation of organic matter, biological nitrification, biological denitrification, chemical precipitation of phosphorus, chemical oxidation of refrac-tory organics and toxic compounds, efficient kill of bacteria and 30 viruses and removal of the unreacted oxidizing agents to render the purified waste water suitable for reuse.
Another object of this invention is to provide a prooess for purification of waste waters, that will not be affected by shock hydraulic and organic loadings.
Another object of this invention is to provide a prooess for purification of waste waters, that will produoe minimum exoess sludge, will require minimum energy and will be capable of unatten-ded operation.
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Other objects and features of the invention will be set forth fully here in after.
The full nature of the invention will be understood from the accom~anying drawings and follcwing description and claims.
SUMM~RY OF THE INVENTICN
The present invention provides a process for purification of waste waters in which the various biological, chemical and physical processes required to remove pollutants can be carried out in a sin-gle sludge system in a single reactor divided by vertical partitions into independent reaction zones.
Processes carried out in first three reaction zones include:
(a) adsorption of dissolved organic matter by fluidized suspended solids, (b) bio-oxidation of biodegradable organic matter i.e. heterotrophic oxidation, autotrophic oxidation and endogenous respiration, (c) ammonification followed by biological nitrification simulta-neously with respiratory denitrification, (d) chemical precipitation of phosphorus by added mineral along with adsorption of phosphorus by fluidized bed suspended solids, (e) continuous separation of the fluidized bed solids from the pur-ified waste water and recirculation of the fluidized bed solids between the three reaction zones.
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The processes ~rried out in the fourth reaction zone include:
(a) chemical oxidation of the residual organics and toxic compounds by chemical oxidizing agents such as potassium permanganate and/or chlorine, (b) kill of bacteria and viruses by added oxidizing agents, (c) chemical precipitation of metal ions and/or salts by added oxidiz-ing agents, 10~4~
(d) separation of precipitates and/or residual suspended solids en-trained frvm third reaction zone by settling.
m e chemical decomposition of the unreacted oxidizing agents by reaction of the agents with charooal is carried out in the fifth reaction zone.
It has been proved that if the processes of bio-oxidation, amn~-nification, nitrification and denitrification are carried out in the presence of fluidized suspended solids the process performance and the purity of the processed waste water is improved. The rela-tively fast settling fluidized bed solids have a tendency to coa-gulate into large flocs entrapping the micro-organisms and colloi-dal and suspended matter present in the waste water. The resulting sludge has higher density than the conventional activated sludge prooe ss sludge and exhibits filtration effect that improves the efficiency of separation of mixed microbial population and suspen-ded solids from purified waste water. The controlled exposure of the micro-organisms to food and oxygen in the presen oe of fluidized sus-pended solids as described in this invention permits re~.oval of organic and nitrogenous compounds in a single sludge system to-gether with chemical precipitation in a simple process sequence easily adaptable for use in small size package plants. Cbmbined with chemical oxidation of residual organics carried out as indica-ted in this invention the purification process of this invention ; produoes an effluent suitable for limited reuse.
DESCRIPTICN OF THE DR~INGS
m e aforementioned and other objects, advantages and features of the invention will become apparent in the follcwing detailed descrip~ion of the preferred embodlment as shown in the drawings wherein:
Figure 1 is a schematic representation of the purification prooe ss of this invention showing a vertical cut away view through the reaction zones used in accordan oe with this invention.
Figure 2 is a schematic representation of the purification pro-oe ss of this invention showing a horizontal lay-out of the reaction zones used in accordan oe with this invention.
Figure 3 is a graph showing the settling rate of various active media - sludges suitable for use in the process of this invention.
DESCRIPTICN OE THE rNVE~TlON
The removal of suspended solids, bio-oxidation of organic matter, ammonification, biological nitrification and biological denitrification of nitrogenous compounds and chemical precipitation of phosphorus from the incoming waste water is achieved in three reaction zones each con-taining fluidized bed of nondegradable suspended solids and mixed micro-bial population, with the fluidized bed suspended solids being circulated from third reaction zone to first reaction zone then from first reaction zone to second reaction zone and from second to third reaction zone. The biochemical reactions occurring in these three reaction zones are listed in Table 1.
Excluding the synthesized nitrogen the removal of nitrogen is via steps of biological nitrification followed by denitrification with most of the nitrite nitrogenous material being converted to nitrogenous gas through respiration of the mixed microbial population.
The conditions that make the reactions of bio-oxidation and nitri-fication requiring oxygen and the respiratory denitrification re-quiring absence of oxygen in the pro oess of this invention possible are:
(a) the active micr~bial population responsible for bio-oxidation of organic matter, nitrification and respiratory denitrifica-tion is entrapped into fluidized bed suspended solids, (b) the microbial population, fluidized bed suspended solids and portion of treated waste water is being circulated between reaction zones in the d;rection from third reaction zone to first, to second and to third reaction zone, (c) the microbial population on its way through the three reac-tion zones is exposed to an environmental cycle composed of:
i -contact of the micro-organisms with food in absen oe of di-solved o~ygen in the first reaction zone, ii -exposure of the micro-organisms to oxygen in the second reac-tion zone, and iii-oontact of the treated waste water containing nitrite and/or nitrate nitrogenous material with mixed microbial popula-tion in absen oe of oxygen and in presence of organic mate-rial adsorbed on the fluidized bed suspended solids in the third reaction zone.
(d) a suitable soluble mineral not interfering with biochemical reactions and capable of precipitating phosphorus and other metal ions is being added into the fluidized bed established in second reaction zone, and (e) the separation of the microbial population and fluidized bed susFended solids from the purified waste waier is achieved by a submerged suspended solids separator located in the third reaction zone.
: The schematic diagram of the process of this invention is shown in Figure 1 and Figure 2. AS seen from Figure 1 and Figure 2 the purification process of this invention is carried out in a single reaction tank 1 separated by partitions into first reaction zone 100, second reaction zone 200, third reaction zone 300, fourth reaction zone 400 and fifth reaction zone 500.
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The first reaction zone is in communication with the second reaction zone 200 by restricted opening 109 in the common partition 110 separating the first reaction zone fro~ the second reaction zone, the second reaction zone 200 being in cQmn~nicatiOn with third reac-tion zone 300 by restricted opening 209 in the common partition 210 separating the second reaction zone from the third reaction zone, the third reaction zone 300 being in comnunication with first reaction zone 100 by restricted opening 107 in common partition 110 separating the third reaction zone 300 from the first reaction zone 100 and third reaction zone 300 being in communication with fouLth reaction zone 400 through submerged multichannel suspended solids separator 310 located in the third reaction zone 300, the third reaction zone 300 being se-parated frQm the fourth reaction zone 400 by a common partition 315 between the third and fourth reaction zones, and the fourth reaction zone 400 being in ccmmMnication with the fifth reaction zone 500 by 25 a restricted opening 409 in the co n partition 415 separating the fourth reaction zone 400 frQm the fifth reaction zone 500.
Fluidized bed 101, 201 and 301 is established in reaction zones 100, 200 and 300 by adding into the reaction zones initially fine wood particles such as sawdust and by accumulating the nonbiodegrad-able suspended solids present in the waste water and by accumNlating the formed precipitates and by accumulating the excess biological solids formed during biological oxidation of the organic matter in reaction zones 100, 200 and 300.
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me fluidized bed 101 in first reaction zone 100 is maintained by recirculating of a portion of the suspension from the upper level of the fluidized bed 101 dcwnwardly in recirculation pipe 102 to the bottom 103 of the reaction zone 100 then upwardly through the fluid-ized bed 101 in direction of arrows 104. The recirculation of the suspension in first reaction zone 100 is maintained by a submerged propeller 105 located in recirculation pipe 102 in a way in which there is no addition of air or oxygen into the recirculated sus-pension and therefore the concentration of dissolved oxygen in the liquid in fluidized bed 101 is maintained at close to zero mg~L. Sim-ultaneously a portion of suspension 106 from third reaction zone 300 is being circulated into the first reaction zone 100 via opening 107, the flow being maintained in the range from 50 to 200 percent of in-coming waste water. The recycled suspension 106 contains mixed micro-bial population, precipitates, wcod particles, nonbiodegradable sus-pended solids and purified waste water containing remaining nitrite and/or nitrate nitrogenous material. The chemically bound oxygen in the nitrite and/or nitrate nitrogenous material recycled with the suspension 106 from reaction zone 300 into fluidized bed 101 is used up in the respiration chain by the mixed microbial population kept in fluidized bed 101.
The incaming waste water 10 enters into first reaction zone 100 where it is mixed with mixed microbial population, wood particles, nonbiodegradable suspended solids, precipitates and purified waste water in fluidized bed 101. The activity of micro-organisms in flui-- dized bed 101 is being increased by the dissolved organic matter pre-sent in the inco~ing sewage causing complete degradation of nitrite and/or nitrate nitrogenous material present in the fluidized bed 101.
In fluidized bed 101 portion of the dissolved organic matter present in the inoamung waste water is absorbed into the micrDbial cells, portion is bio-oxidized to carbon dioxide and portion is adsorbed by the fluidized particles. Simultaneously the dissolved organic nitro-genous material is transformed by mixed microbial population kept in fluidized bed 101 to a~monia with small portion of the ammonia meta-bolized and small portion transformed through nitrite to nitrogenous - gas. SinLltaneously, portion of soluble phosphates present in the incoming waste water is metabolized and a small portion adsorbed by the fluidized bed particles.
From the first reaction zone 100 the suspension containing mixed microbial population, fluidized bed particles and partially purified waste water flows by gravity via opening 109 into second reaction zone 200 where it is mixed in fluidized bed 201 with mixed microbial popula-tion, fluidized bed particles, partially purified waste water, addeddissolved mineral and added diffused air. The fluidized bed in the second aeration zone 200 is maintained by recirculating a portion of suspension from the upper level of the fluidized bed 201 downwardly in recirculation pipe 202 to the bottom 203 of the reaction zone 200, then upwardly through the fluidized bed 201 in ~;rection of arrows 204. The recirculation of the suspension is maintained by submerged propeller 205 located in recirculation pipe 202. The propeller 205 is equipped by an air intake pipe 206 and sim~ltaneously injects into the recircu-lated suspension atmospheric air which is then mixed in recirculation pipe 202 with the recirculated suspension, then flown in pipe 202 down-wardly to the bottom 203 of the reaction zone 200 then upwardly through fluidized bed 201 and finally out to atmosphere. On itis way through recirculation pipe 202 and fluidized bed 201 the oxygen from the air is being absorbed into the recirculated liquid, into the microbial cells, and adsorbed by the fluidized bed solids, then used up by the mixed microbial population in bio-oxidation of the organic matter present in the partially purified waste water and organic matter adsorbed on the fluidized bed solids, in bio-oxidation of the ammonia to nitrite and/or nitrate and also in chemical oxidation of organic and inorganic solids present in partially purified waste water. The concentration of the dissolved oxygen in fluidized bed 202 is maintained in the range between 1.0 to 2.0 mg/L by controlling of the volume of air injected by propeller 205 through pipe 206. Simultaneously a soluble mineral 208 is added into the fluidized bed 201 to precipitate soluble phosphates present in the partially purified waste water. In fluidized bed 201 the dissolved bio-degradable organic matter is bio-oxidized and the remaining ammonia transformed to nitrite and/or nitrate.
Because of the lcw conoontration of dissolved oxygen in fluidized bed 201, portion of the mineralized nitrogen is also transformed to - 35 nitrogen gas. Simultaneously, the dissolved mineral 208 added into the fluidized bed 201 is precipitating the soluble phosphates and other metal ions present in the partially purified w~ste water.
Fr~m reaction zone 200 the suspension containing mixed microbial population, fluidized bed suspended solids, organic matter adsorbed on fluidized bed solids and the purified waste water oontaining mine-ralized nitrogen is flown by gravity via opening 209 into third reac-tion zone 300 where it is mixed with mixed microbial population, flui-dized bed suspended solids and purified sewage.
The fluidized bed 301 in the third reaction zone 300 is maintained by recirculating a portion of suspension from the upper level of the fluidized bed 301 downwardly in recirculation pipe 302 to the bottom 303 of the reaction zone 300 with portion of the recirculated suspension being diverted into opening 107 and recycled into first reaction zone 100 and with the rest being flownupwardly through the fluidized bed 301 in the direction of arrows 304. The recirculation of the suspension in third reaction zone 300 is maintained by a submerged propeller 305 located in recirculation pipe 302 in a way in which there is no addition of air or oxygen into the recirculated suspension, and the concentration of dissol-ved oxygen in the liquid in fludized bed 301 due to the activity of the mixed microbial population kept influidized bed 301 is maintained at close to zero mg/L. The activity of the mixed microbial population in fluidized bed 301 is supported substantially by the organic matter adsorbed on the fluidized bed suspended solids flown with the waste water from first reaction zone 100 into second reaction zone 200 and from second reaction zone 200 into third reaction zone 300. In fluidized bed 301 the adsorbed organic matter is bio-oxidized and the nitrite and/or nitrate nitrogenous material is decomFosed to nitrogenous gas by respiration by the mixed microbial population. The suspension containing the fluidized bed solids and the purified waste water enters into a submerged multi-channel suspended solids separator 310 in which the suspended solids are separated from the purified waste water and continuously flown by gravity into the fluidized bed 301 and the purified waste water is flown through a flcw equalizer 311 into reaction zone 400. The flcw equalizer 311 con-trols the flow of the purified waste water through the submerged multi-channel suspended solids separator 310 within the designed range regard-less of the flow of the incoming waste water. At a surge flcw of the in-coming waste water the flow equalizer 311 causes to rise the normal operating level of the suspension kept in reaction zones 100, 200 and 300 to a higher level limited only by the space available in the three react-ion zones, with the incoming waste water being substantially accumLlated in reaction zone 100 and the partially purified waste water being sub-stantionally a_cumNlated in reaction zones 200 and 300. During and after the surge at an equalized rate controlled by flow equalizer 311 the pur-ified waste water is being flown through the su~merged multichannel sus-~o~
pended solids separato~ 310 into the fourth reaction zone 400 with the level of suspension in reaction zones 100, 200, 300 being re-turned to the pre-surge hight. In this way the detrimental effect of the hydraulic and BOD surge loadings on the involved biological, chemical and physical prccesses in the purification process of this invention is eliminated.
As the purified waste water containing residual refractory or-ganics, bacteria and viruses flows out of reaction zone 300 into reaction zone 400, oxidizing agents 401 potassium permanganate or chlorine or their mixture i.e. permanganate and hypochlorite is added to the purified waste water. Sufficient retention time is provided in reaction zone 400 to substantially completely oxidize the residual organics, to kill bacteria and viruses and to settle out the formed or entrained suspended solids.
From reaction zone 400 the purified waste water o~ntaining un-reacted oxidizing agent flows by gravity via opening 409 into re-action zone 500 containing a bed of granular charcoal 501. In con-tact with charcoal 501 the unreacted oxidizing agents present in the purified waste water are decomposed to harmless products and the purified waste water is flown out of reaction zone 500 via line 502 for disposal or for reuse.
Figure 3 illustrates the settling rate of different active media-sludges and the settling rate of the fluidized bed particles used in the purification process of this invention.
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It will be seen therefore, that the process of the present in-vention is able to remove substantially completely carbonaceous, nit-rogenous and suspended solids, phosphorus, bacteria and viruses from waste waters containing such contaminants while avDiding the pr~duction of substantial quantities of ex oess biological sludge, in a simple seq-uen oe and in a simple equipnent requiring little space and essencially no maintenan oe. Capital end operating costs are therefore significantly lcwer than with any other known waste water renovation treatment. Mod-ifications are possible within the scope of the present invention.
"Prooess for Purification of Sanitary Waters"
` :
- FIELD OF INVENIION
This invention relates to purification of waste waters, parti-cularly to removal of pollutants such as suspended solids, carbona-ceous material, nitrogenous material, phosphorus, bacteria and vi-ruses present in domestic waste waters.
The prooe ss of this invention utilizes fluidized nonbiodegrad-able suspended solids to increase the concentration of mixed micro-~- bial population in the reaction system to improve the efficiency of biochemical reactions, to improve the efficiency of chemical preci-pitation of phosphorus through more efficient coagulation of the for-med precipitates and through adsorption of phosphorus on the flui-dized suspended solids and to improve the efficiency of separation of suspended solids from the purified wasteswater by coagulation of the solids into large floccs retained in the fluidized bed.
The pracess hydraulics permits better control of the environ-mental conditions required by the microbial population and the si-multaneously occurring bio-oxidation reactions requiring oxygen and denitrification reactions requiring absen oe of oxygen.
BACKGROUND TO THE INVENTION
It has beco~e evident that nitrogen and phosphorus affect the productivity of aquatic life - nitrogen being the limiting nutrient in eutrophic waters and phosphorus in oligotrophic waters.
It is also known that municipal waste waters contain from 10 to 100 times the nutrient concentration of agricultural or forest drainage. Consequently in densely populated areas overfertilization of surfaoe waters, algae growth and chemical pollution have been no-ticed along with degradation of potable water sources and the need for m~re efficient removal of organics, nitrogenous ccmpounds and phosphorus from all waste waters has become more obvious.
While removal of phosphorus can be achieved reliably by chemi-cal precipitation and removal of organics by biological follcwed by physical chemical prooesses, removal of nitrogen is more complicated.
~ q3 m e current processes of ammonia stripping, break ~oint chlo-rination, ion exchange and biological nitrification followed by biological denitrification are relatively oomplex and expensive.
Although conventional activated sludge prooe ss is capable of removing up to 50 - 60 percent of the nitrogen frc~ treated waste waters, the removal of nitrogen is eratic and in most cases it's major part is discharged in mineralized form in the effluent.
The biologieal transformations of nitrogenous compounds occure through biological pro oesses of am~onification, nitrification and denitrification. The first two require presen oe of oxygen, the de-nitrification require absenoe of oxygen. The two distinct mechan-isms responsible for removal of nitrogen and reduction of nitrite and nitrate are (a) - formation of ammonia followed by transfer of ammonia into the anabolic oe ll metabolism which is of minor impor-tanee sinee C:N ratio in eell tissue is 5 - 6, whereas in domestie waste waters only 2- 2.5, and (b) - mierobial denitrification, which is a respiratory reduction is whieh nitrite and nitrate rep-laoe oxygen as the final eleetron acoeptors in the respiration chain.
Considerable number of heterotrophic faeultative and obligate anaerobie baeteria speeies ean transfer eleetrons to nitrite in-stead of oxygen in the respiratory ehain, and all substrates nor-mally used by the eells for respiration may serve as eleetron do-nors for the reduetion proeess regardless of whether they are pre-sent in the external medium, or whether they have to be mobiliz~d from intraoellular assimilates.
m e reduetion of nitrate is eonsidered to be an adaptive pro-perty of those baeteria that ean reduoe nitrite for respiration.
The reduetion meehanism for bio-oxidation of organie matter and for transformation of the nitrogenous ecmpounds is expressed by reactions listed in Table 1.
Bio-oxidation of organie matter, ammonifieation and nitrifiea-tion eause no problems. Nitrifieation is effieient and reliable if organie loadings are maintained below 0.3 lb BOD per lb of mixed liquor suspended solids per day, sludge age is maintained above 3-4 days and dissolved oxygen in the mixed liquor is maintained above 1.0 - 2.0 mg/L. Ihe higher is the concentration of mixed liquor sus-pended solids, the more efficient is the transformation of ammonia to nitrite and nitrate. The overall rate of denitrification is a function of the concentration of the heterotrophic facultative bacteria present in mixed liquor suspended solids and their activity in the absen oe of oxygen. To maintain the activity the denitrifying bacteria must be supplied with suitable organic material - source of energy.
Yrom the process point of view to accomodate the different food and oxygen requirements of bio-oxidation of organic matter, ammoni-fication and nitrification of nitrogenous compounds and decomposi-tion of nitrite and nitrate by the microbial respiration and to achieve acoeptable reaction rates and efficiencies, the various biochemical reactions are currently being carried out in separate pro oess stages.
While the eonventional activated sludge process is capable of remov-ing nitrogen with effieiency of 50 - 60 peroent, the current multi-stage processes ean achieve the removal of nitrogen with efficiency up to 80 - 90 peroent.
The multistage prooesses currently in use in large munieipal treatment plants require treatment facilities that are too eomplex to be scaled dcwn to small package plants to serve small develop-ments or single family dwellings. More, the established biological processes are inefficient in removal of biologically resistant ccm-pounds recognized as refractory organics and the Physical-ehemical treatments are ineffieient in removal of low organic acids and low carbohydrates both highly soluble and present in considerable con-oentrations in domestie and munieipal waste waters. ConsequentLy neither the biological, nor the ehemical - physical treatments alone can effieiently reduce the coneentration of organic contaminants to the level found in fresh waters. The required combination of the bio-logieal and physical - chemical treatments therefore further inerea-ses the complexity of the treatment and the treatment faeilities.
Furthermore, biological pro oesses that utilize low organie loa-dings to achieve low yields generate sludges that have poor coagu-lation properties, requiring low overflow rates in elarifiers and eausing relatively high losses of solids in effluents.
Because of the number of process steps required for removal of the various pollutants renovation and reuse of d estie waste waters at present seems feasible only if praetieed on a large seale.
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A large waste water treatment - renovation plant however requi-res large underground sewage collection - transportationnetwork, and in case the renovated water is reused a large underground water distribution network. Such netwDrks are expensive to build and even 5 more expensive to maintain and to operate.
It is therefore obvious that on-site renovation and reuse of waste water would be economically more attractive than renovation and reuse of waste waters via central collection-treatment-distri-bution. However, because of the camplexity of the involved treat-i 10 ment on-site renovation and reuse of domestic waste water as yet can't be practiced.
Although, at present small package sewage treatment plants are available, they do not provide the required degree of purification that would permit reuse of the purified effluent and in general they 15 also lack the required process stability.
It is therefore the prime object of this invention to reduoe the number of process steps required by the present art and carried out in separate process stages when removing suspended solids, carbona-oeous material, nitrogenous material, phosphorus, bacteria and vi- I
20 ruses fram domestic waste waters and to provide a purification pro-cess having a simple process sequence and capable of rem~ving the various pollutants more-less simultaneously.
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MDre particularly it is the object of this invention to provide a process for purification of sanitary waters and purification of 25 some industrial waste waters, which would be capable of achieving reliable and efficient removal of suspended solids, bio-oxidation of organic matter, biological nitrification, biological denitrification, chemical precipitation of phosphorus, chemical oxidation of refrac-tory organics and toxic compounds, efficient kill of bacteria and 30 viruses and removal of the unreacted oxidizing agents to render the purified waste water suitable for reuse.
Another object of this invention is to provide a prooess for purification of waste waters, that will not be affected by shock hydraulic and organic loadings.
Another object of this invention is to provide a prooess for purification of waste waters, that will produoe minimum exoess sludge, will require minimum energy and will be capable of unatten-ded operation.
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Other objects and features of the invention will be set forth fully here in after.
The full nature of the invention will be understood from the accom~anying drawings and follcwing description and claims.
SUMM~RY OF THE INVENTICN
The present invention provides a process for purification of waste waters in which the various biological, chemical and physical processes required to remove pollutants can be carried out in a sin-gle sludge system in a single reactor divided by vertical partitions into independent reaction zones.
Processes carried out in first three reaction zones include:
(a) adsorption of dissolved organic matter by fluidized suspended solids, (b) bio-oxidation of biodegradable organic matter i.e. heterotrophic oxidation, autotrophic oxidation and endogenous respiration, (c) ammonification followed by biological nitrification simulta-neously with respiratory denitrification, (d) chemical precipitation of phosphorus by added mineral along with adsorption of phosphorus by fluidized bed suspended solids, (e) continuous separation of the fluidized bed solids from the pur-ified waste water and recirculation of the fluidized bed solids between the three reaction zones.
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The processes ~rried out in the fourth reaction zone include:
(a) chemical oxidation of the residual organics and toxic compounds by chemical oxidizing agents such as potassium permanganate and/or chlorine, (b) kill of bacteria and viruses by added oxidizing agents, (c) chemical precipitation of metal ions and/or salts by added oxidiz-ing agents, 10~4~
(d) separation of precipitates and/or residual suspended solids en-trained frvm third reaction zone by settling.
m e chemical decomposition of the unreacted oxidizing agents by reaction of the agents with charooal is carried out in the fifth reaction zone.
It has been proved that if the processes of bio-oxidation, amn~-nification, nitrification and denitrification are carried out in the presence of fluidized suspended solids the process performance and the purity of the processed waste water is improved. The rela-tively fast settling fluidized bed solids have a tendency to coa-gulate into large flocs entrapping the micro-organisms and colloi-dal and suspended matter present in the waste water. The resulting sludge has higher density than the conventional activated sludge prooe ss sludge and exhibits filtration effect that improves the efficiency of separation of mixed microbial population and suspen-ded solids from purified waste water. The controlled exposure of the micro-organisms to food and oxygen in the presen oe of fluidized sus-pended solids as described in this invention permits re~.oval of organic and nitrogenous compounds in a single sludge system to-gether with chemical precipitation in a simple process sequence easily adaptable for use in small size package plants. Cbmbined with chemical oxidation of residual organics carried out as indica-ted in this invention the purification process of this invention ; produoes an effluent suitable for limited reuse.
DESCRIPTICN OF THE DR~INGS
m e aforementioned and other objects, advantages and features of the invention will become apparent in the follcwing detailed descrip~ion of the preferred embodlment as shown in the drawings wherein:
Figure 1 is a schematic representation of the purification prooe ss of this invention showing a vertical cut away view through the reaction zones used in accordan oe with this invention.
Figure 2 is a schematic representation of the purification pro-oe ss of this invention showing a horizontal lay-out of the reaction zones used in accordan oe with this invention.
Figure 3 is a graph showing the settling rate of various active media - sludges suitable for use in the process of this invention.
DESCRIPTICN OE THE rNVE~TlON
The removal of suspended solids, bio-oxidation of organic matter, ammonification, biological nitrification and biological denitrification of nitrogenous compounds and chemical precipitation of phosphorus from the incoming waste water is achieved in three reaction zones each con-taining fluidized bed of nondegradable suspended solids and mixed micro-bial population, with the fluidized bed suspended solids being circulated from third reaction zone to first reaction zone then from first reaction zone to second reaction zone and from second to third reaction zone. The biochemical reactions occurring in these three reaction zones are listed in Table 1.
Excluding the synthesized nitrogen the removal of nitrogen is via steps of biological nitrification followed by denitrification with most of the nitrite nitrogenous material being converted to nitrogenous gas through respiration of the mixed microbial population.
The conditions that make the reactions of bio-oxidation and nitri-fication requiring oxygen and the respiratory denitrification re-quiring absence of oxygen in the pro oess of this invention possible are:
(a) the active micr~bial population responsible for bio-oxidation of organic matter, nitrification and respiratory denitrifica-tion is entrapped into fluidized bed suspended solids, (b) the microbial population, fluidized bed suspended solids and portion of treated waste water is being circulated between reaction zones in the d;rection from third reaction zone to first, to second and to third reaction zone, (c) the microbial population on its way through the three reac-tion zones is exposed to an environmental cycle composed of:
i -contact of the micro-organisms with food in absen oe of di-solved o~ygen in the first reaction zone, ii -exposure of the micro-organisms to oxygen in the second reac-tion zone, and iii-oontact of the treated waste water containing nitrite and/or nitrate nitrogenous material with mixed microbial popula-tion in absen oe of oxygen and in presence of organic mate-rial adsorbed on the fluidized bed suspended solids in the third reaction zone.
(d) a suitable soluble mineral not interfering with biochemical reactions and capable of precipitating phosphorus and other metal ions is being added into the fluidized bed established in second reaction zone, and (e) the separation of the microbial population and fluidized bed susFended solids from the purified waste waier is achieved by a submerged suspended solids separator located in the third reaction zone.
: The schematic diagram of the process of this invention is shown in Figure 1 and Figure 2. AS seen from Figure 1 and Figure 2 the purification process of this invention is carried out in a single reaction tank 1 separated by partitions into first reaction zone 100, second reaction zone 200, third reaction zone 300, fourth reaction zone 400 and fifth reaction zone 500.
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The first reaction zone is in communication with the second reaction zone 200 by restricted opening 109 in the common partition 110 separating the first reaction zone fro~ the second reaction zone, the second reaction zone 200 being in cQmn~nicatiOn with third reac-tion zone 300 by restricted opening 209 in the common partition 210 separating the second reaction zone from the third reaction zone, the third reaction zone 300 being in comnunication with first reaction zone 100 by restricted opening 107 in common partition 110 separating the third reaction zone 300 from the first reaction zone 100 and third reaction zone 300 being in communication with fouLth reaction zone 400 through submerged multichannel suspended solids separator 310 located in the third reaction zone 300, the third reaction zone 300 being se-parated frQm the fourth reaction zone 400 by a common partition 315 between the third and fourth reaction zones, and the fourth reaction zone 400 being in ccmmMnication with the fifth reaction zone 500 by 25 a restricted opening 409 in the co n partition 415 separating the fourth reaction zone 400 frQm the fifth reaction zone 500.
Fluidized bed 101, 201 and 301 is established in reaction zones 100, 200 and 300 by adding into the reaction zones initially fine wood particles such as sawdust and by accumulating the nonbiodegrad-able suspended solids present in the waste water and by accumNlating the formed precipitates and by accumulating the excess biological solids formed during biological oxidation of the organic matter in reaction zones 100, 200 and 300.
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me fluidized bed 101 in first reaction zone 100 is maintained by recirculating of a portion of the suspension from the upper level of the fluidized bed 101 dcwnwardly in recirculation pipe 102 to the bottom 103 of the reaction zone 100 then upwardly through the fluid-ized bed 101 in direction of arrows 104. The recirculation of the suspension in first reaction zone 100 is maintained by a submerged propeller 105 located in recirculation pipe 102 in a way in which there is no addition of air or oxygen into the recirculated sus-pension and therefore the concentration of dissolved oxygen in the liquid in fluidized bed 101 is maintained at close to zero mg~L. Sim-ultaneously a portion of suspension 106 from third reaction zone 300 is being circulated into the first reaction zone 100 via opening 107, the flow being maintained in the range from 50 to 200 percent of in-coming waste water. The recycled suspension 106 contains mixed micro-bial population, precipitates, wcod particles, nonbiodegradable sus-pended solids and purified waste water containing remaining nitrite and/or nitrate nitrogenous material. The chemically bound oxygen in the nitrite and/or nitrate nitrogenous material recycled with the suspension 106 from reaction zone 300 into fluidized bed 101 is used up in the respiration chain by the mixed microbial population kept in fluidized bed 101.
The incaming waste water 10 enters into first reaction zone 100 where it is mixed with mixed microbial population, wood particles, nonbiodegradable suspended solids, precipitates and purified waste water in fluidized bed 101. The activity of micro-organisms in flui-- dized bed 101 is being increased by the dissolved organic matter pre-sent in the inco~ing sewage causing complete degradation of nitrite and/or nitrate nitrogenous material present in the fluidized bed 101.
In fluidized bed 101 portion of the dissolved organic matter present in the inoamung waste water is absorbed into the micrDbial cells, portion is bio-oxidized to carbon dioxide and portion is adsorbed by the fluidized particles. Simultaneously the dissolved organic nitro-genous material is transformed by mixed microbial population kept in fluidized bed 101 to a~monia with small portion of the ammonia meta-bolized and small portion transformed through nitrite to nitrogenous - gas. SinLltaneously, portion of soluble phosphates present in the incoming waste water is metabolized and a small portion adsorbed by the fluidized bed particles.
From the first reaction zone 100 the suspension containing mixed microbial population, fluidized bed particles and partially purified waste water flows by gravity via opening 109 into second reaction zone 200 where it is mixed in fluidized bed 201 with mixed microbial popula-tion, fluidized bed particles, partially purified waste water, addeddissolved mineral and added diffused air. The fluidized bed in the second aeration zone 200 is maintained by recirculating a portion of suspension from the upper level of the fluidized bed 201 downwardly in recirculation pipe 202 to the bottom 203 of the reaction zone 200, then upwardly through the fluidized bed 201 in ~;rection of arrows 204. The recirculation of the suspension is maintained by submerged propeller 205 located in recirculation pipe 202. The propeller 205 is equipped by an air intake pipe 206 and sim~ltaneously injects into the recircu-lated suspension atmospheric air which is then mixed in recirculation pipe 202 with the recirculated suspension, then flown in pipe 202 down-wardly to the bottom 203 of the reaction zone 200 then upwardly through fluidized bed 201 and finally out to atmosphere. On itis way through recirculation pipe 202 and fluidized bed 201 the oxygen from the air is being absorbed into the recirculated liquid, into the microbial cells, and adsorbed by the fluidized bed solids, then used up by the mixed microbial population in bio-oxidation of the organic matter present in the partially purified waste water and organic matter adsorbed on the fluidized bed solids, in bio-oxidation of the ammonia to nitrite and/or nitrate and also in chemical oxidation of organic and inorganic solids present in partially purified waste water. The concentration of the dissolved oxygen in fluidized bed 202 is maintained in the range between 1.0 to 2.0 mg/L by controlling of the volume of air injected by propeller 205 through pipe 206. Simultaneously a soluble mineral 208 is added into the fluidized bed 201 to precipitate soluble phosphates present in the partially purified waste water. In fluidized bed 201 the dissolved bio-degradable organic matter is bio-oxidized and the remaining ammonia transformed to nitrite and/or nitrate.
Because of the lcw conoontration of dissolved oxygen in fluidized bed 201, portion of the mineralized nitrogen is also transformed to - 35 nitrogen gas. Simultaneously, the dissolved mineral 208 added into the fluidized bed 201 is precipitating the soluble phosphates and other metal ions present in the partially purified w~ste water.
Fr~m reaction zone 200 the suspension containing mixed microbial population, fluidized bed suspended solids, organic matter adsorbed on fluidized bed solids and the purified waste water oontaining mine-ralized nitrogen is flown by gravity via opening 209 into third reac-tion zone 300 where it is mixed with mixed microbial population, flui-dized bed suspended solids and purified sewage.
The fluidized bed 301 in the third reaction zone 300 is maintained by recirculating a portion of suspension from the upper level of the fluidized bed 301 downwardly in recirculation pipe 302 to the bottom 303 of the reaction zone 300 with portion of the recirculated suspension being diverted into opening 107 and recycled into first reaction zone 100 and with the rest being flownupwardly through the fluidized bed 301 in the direction of arrows 304. The recirculation of the suspension in third reaction zone 300 is maintained by a submerged propeller 305 located in recirculation pipe 302 in a way in which there is no addition of air or oxygen into the recirculated suspension, and the concentration of dissol-ved oxygen in the liquid in fludized bed 301 due to the activity of the mixed microbial population kept influidized bed 301 is maintained at close to zero mg/L. The activity of the mixed microbial population in fluidized bed 301 is supported substantially by the organic matter adsorbed on the fluidized bed suspended solids flown with the waste water from first reaction zone 100 into second reaction zone 200 and from second reaction zone 200 into third reaction zone 300. In fluidized bed 301 the adsorbed organic matter is bio-oxidized and the nitrite and/or nitrate nitrogenous material is decomFosed to nitrogenous gas by respiration by the mixed microbial population. The suspension containing the fluidized bed solids and the purified waste water enters into a submerged multi-channel suspended solids separator 310 in which the suspended solids are separated from the purified waste water and continuously flown by gravity into the fluidized bed 301 and the purified waste water is flown through a flcw equalizer 311 into reaction zone 400. The flcw equalizer 311 con-trols the flow of the purified waste water through the submerged multi-channel suspended solids separator 310 within the designed range regard-less of the flow of the incoming waste water. At a surge flcw of the in-coming waste water the flow equalizer 311 causes to rise the normal operating level of the suspension kept in reaction zones 100, 200 and 300 to a higher level limited only by the space available in the three react-ion zones, with the incoming waste water being substantially accumLlated in reaction zone 100 and the partially purified waste water being sub-stantionally a_cumNlated in reaction zones 200 and 300. During and after the surge at an equalized rate controlled by flow equalizer 311 the pur-ified waste water is being flown through the su~merged multichannel sus-~o~
pended solids separato~ 310 into the fourth reaction zone 400 with the level of suspension in reaction zones 100, 200, 300 being re-turned to the pre-surge hight. In this way the detrimental effect of the hydraulic and BOD surge loadings on the involved biological, chemical and physical prccesses in the purification process of this invention is eliminated.
As the purified waste water containing residual refractory or-ganics, bacteria and viruses flows out of reaction zone 300 into reaction zone 400, oxidizing agents 401 potassium permanganate or chlorine or their mixture i.e. permanganate and hypochlorite is added to the purified waste water. Sufficient retention time is provided in reaction zone 400 to substantially completely oxidize the residual organics, to kill bacteria and viruses and to settle out the formed or entrained suspended solids.
From reaction zone 400 the purified waste water o~ntaining un-reacted oxidizing agent flows by gravity via opening 409 into re-action zone 500 containing a bed of granular charcoal 501. In con-tact with charcoal 501 the unreacted oxidizing agents present in the purified waste water are decomposed to harmless products and the purified waste water is flown out of reaction zone 500 via line 502 for disposal or for reuse.
Figure 3 illustrates the settling rate of different active media-sludges and the settling rate of the fluidized bed particles used in the purification process of this invention.
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It will be seen therefore, that the process of the present in-vention is able to remove substantially completely carbonaceous, nit-rogenous and suspended solids, phosphorus, bacteria and viruses from waste waters containing such contaminants while avDiding the pr~duction of substantial quantities of ex oess biological sludge, in a simple seq-uen oe and in a simple equipnent requiring little space and essencially no maintenan oe. Capital end operating costs are therefore significantly lcwer than with any other known waste water renovation treatment. Mod-ifications are possible within the scope of the present invention.
Claims (4)
1. A process for the purification of waste waters containing carbona-oeous materials, nitrogenous materials, phosphorus and suspended solids in a single reaction tank which comprises of:
a) separating the reaction tank by vertical partitions into first reaction zone, second reaction zone and third reaction zone, the first reaction zone being in communication with the second reaction zone by a restricted opening in the common partition separating the first reaction zone from the second reaction zone, the second reaction zone being in communication with third reaction zone by restricted opening in the common partition separating the second reaction zone from the third reaction zone, the third reaction zone being in communication with the first reaction zone by a channel and restricted ope-ning in the common partition separating the third reaction zone from the first reaction zone, said third reaction zone being in communication with an exit effluent line via submerged multi-channel suspended solids separator located in third reaction zone, said submerged multichannel suspended solids separator equipped with means equalizing the flow of the purified waste water through the submerged suspended solids separator, said purified waste water flowing out of said third reaction zone being further treated or disposed of, b) establishing in first reaction zone, second reaction zone and third reaction zone fluidized beds, said fluidized bed in said first reaction zone, second reaction zone and third reaction zone being formed by addition of fine wood particles into the reaction zones before or during start-up of the purification process and by accumulating the nonbiodegradable suspended solids present in the waste water, and by accumulating the precipitates formed in precipitating the phosphates from the processed waste water, and by accumulating the excess bio-logical solids formed during biological oxidation of the or-ganic matter present in the processed waste water, said fluid-ized bed in each reaction zone being maintained by flow path of the suspension downwardly from the upper level of the fluid-ized bed in a recirculation pipe to the lower level of the fluidized bed, then upwardly through the fluidized bed, said recirculation of the suspension in first reaction zone and third reaction zone being maintained by a submerged propeller loc-ated in the recirculation pipe without adding atmospheric air into the recirculated suspension and maintaining the concentration of the dissolved oxygen in said first and third reaction zones at close to zero mg/L, said recirculation of the suspension in the second reaction zone being maintained by a submerged propeller located in the re-circulation pipe and equipped with an air intake pipe simultaneously injecting into the recirculated suspension atmospheric air to provide partial saturation of the recirculating suspension with oxygen and maintaining the concentration of the dissolved oxygen in the second reaction zone between 1.0 and 3.0 mg/L., c) adding into the fluidized bed established in the second reaction zone continuously soluble mineral to precipitate the various phosphates present in the incoming waste water, to_ coagulate and flocculate the colloidal matter present in the incoming waste water and to flocculate the fine suspended solids retained in said fluidized bed established in said first, second and third reaction zones, d) circulating a portion of the fluidized bed suspended solids from the first reaction zone into the second reaction zone, from said second reaction zone into third reaction zone and from said third reaction zone into said first reaction zone, e) flowing the incoming waste water into the fluidized bed established in said first reaction zone and mixing said waste water in said fluid-ized bed with the fluidized fine wood particles, nonbiodegradable suspended solids, mixed microbial population and re-cycled purified waste water, f) controlling the retention time of said mixture of waste water and fluidized bed suspended solids in said first reaction zone to carry out during said retention time in said fluidized bed in said first reaction zone simultaneously the processes of:
i. adsorption of the dissolved carbonaceous material on sur-faces of the fluidized bed suspended solids.
ii absorption of a portion of the dissolved carbonaceous mat-erial ammonia and phosphorus into microbial cells.
iii. adsorption of a portion of soluble phosphates on to surfaces of said fluidized bed solids.
iv. biological respiratory denitrification of nitrite and ni-trate nitrogenous material to nitrogen gas.
v. biological oxidation of a portion of dissolved carbonaceous material and a portion of the non-nitrite and/or non-nitrate nitrogenous material using up the oxygen present in the in-coming waste water and the chemically bound oxygen in said nitrite and/or nitrate nitrogenous material, and vi. hydrolysis of the fluidized bed suspended solids.
g) allowing the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said first reaction zone co-currently to said suspension flow and separating the gases from said suspension at the upper level of the fluidized bed and releasing said gases to atmosphere, h) flowing the mixture of partially purified waste water and the fluid-ized bed solids by gravity from said first reaction zone into said second reaction zone, mixing said mixture in said fluidized bed established in said second reaction zone with fluidized bed solids and with the diffused air injected into the recirculated suspension by said submerged propeller and carrying out in the second reaction zone simultaneously the processes of:
i. bio-oxidation of the remaining dissolved carbonaceous mat-erial present in the partially purified waste water, ii. transformation of remaining non-nitrite and/or non-nitrate nitrogenous material to nitrite and/or nitrate nitrogenous material, iii. partial respiratory degradation of the nitrite and/or nitrate nitrogenous material to nitrogenous gas, iv. chemical precipitation of phosphates and free metal ions from the partially purified waste water by the added dissolved mineral, v. adsorption of a portion of soluble phosphates on the surfaces of the fluidized bed solids, vi. partial bio-oxidation of the carbonaceous material adsorbed on the fluidized bed solids, vii. hydrolysis of a portion of fluidized bed solids, viii. coagulation and flocculation of the colloidal matter present in the partially purified waste water, i) allowing the excess diffused air and the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said second reaction zone co-currently to flow of said suspension and separating the gases from the suspension at the upper level of the fluidized bed and releasing the gases to atmosphere, j) flowing the mixture of partially purified waste water and the fluid-ized bed solids by gravity from said second reaction zone into said third reaction zone, mixing said mixture in said fluidized bed est-ablished in said third reaction zone with the purified waste water and with the fluidized bed solids in absence of dissolved oxygen and carrying out in said third reaction zone simultaneously the processes of:
i) bio-oxidation of the carbonaceous material adsorbed on the surfaces of the fluidized bed solids and bio-oxidation of the carbonaceous material absorbed by the microbial cells, ii) respiratory degradation of the nitrite and/or nitrate nit-rogenous material to nitrogenous gas, iii) bio-oxidation of the dissolved material released into the purified waste water through hydrolysis of said fluidized bed solids, iv) coagulation and flocculation of the colloidal matter present in the fluidized bed, v) separation of the suspended solids from the purified waste water, k) allowing the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said third reaction zone co-currently to said suspension flow and separating the gases from the suspension at the upper level of the fluidized bed and releasing the gases to atmosphere, l) flowing the suspended solids separated from the purified waste water in said third reaction zone together with portion of the purified waste water back into said first reaction zone completing the process cycle and flowing the purified waste water out of said third reaction zone for further treatment or disposal.
a) separating the reaction tank by vertical partitions into first reaction zone, second reaction zone and third reaction zone, the first reaction zone being in communication with the second reaction zone by a restricted opening in the common partition separating the first reaction zone from the second reaction zone, the second reaction zone being in communication with third reaction zone by restricted opening in the common partition separating the second reaction zone from the third reaction zone, the third reaction zone being in communication with the first reaction zone by a channel and restricted ope-ning in the common partition separating the third reaction zone from the first reaction zone, said third reaction zone being in communication with an exit effluent line via submerged multi-channel suspended solids separator located in third reaction zone, said submerged multichannel suspended solids separator equipped with means equalizing the flow of the purified waste water through the submerged suspended solids separator, said purified waste water flowing out of said third reaction zone being further treated or disposed of, b) establishing in first reaction zone, second reaction zone and third reaction zone fluidized beds, said fluidized bed in said first reaction zone, second reaction zone and third reaction zone being formed by addition of fine wood particles into the reaction zones before or during start-up of the purification process and by accumulating the nonbiodegradable suspended solids present in the waste water, and by accumulating the precipitates formed in precipitating the phosphates from the processed waste water, and by accumulating the excess bio-logical solids formed during biological oxidation of the or-ganic matter present in the processed waste water, said fluid-ized bed in each reaction zone being maintained by flow path of the suspension downwardly from the upper level of the fluid-ized bed in a recirculation pipe to the lower level of the fluidized bed, then upwardly through the fluidized bed, said recirculation of the suspension in first reaction zone and third reaction zone being maintained by a submerged propeller loc-ated in the recirculation pipe without adding atmospheric air into the recirculated suspension and maintaining the concentration of the dissolved oxygen in said first and third reaction zones at close to zero mg/L, said recirculation of the suspension in the second reaction zone being maintained by a submerged propeller located in the re-circulation pipe and equipped with an air intake pipe simultaneously injecting into the recirculated suspension atmospheric air to provide partial saturation of the recirculating suspension with oxygen and maintaining the concentration of the dissolved oxygen in the second reaction zone between 1.0 and 3.0 mg/L., c) adding into the fluidized bed established in the second reaction zone continuously soluble mineral to precipitate the various phosphates present in the incoming waste water, to_ coagulate and flocculate the colloidal matter present in the incoming waste water and to flocculate the fine suspended solids retained in said fluidized bed established in said first, second and third reaction zones, d) circulating a portion of the fluidized bed suspended solids from the first reaction zone into the second reaction zone, from said second reaction zone into third reaction zone and from said third reaction zone into said first reaction zone, e) flowing the incoming waste water into the fluidized bed established in said first reaction zone and mixing said waste water in said fluid-ized bed with the fluidized fine wood particles, nonbiodegradable suspended solids, mixed microbial population and re-cycled purified waste water, f) controlling the retention time of said mixture of waste water and fluidized bed suspended solids in said first reaction zone to carry out during said retention time in said fluidized bed in said first reaction zone simultaneously the processes of:
i. adsorption of the dissolved carbonaceous material on sur-faces of the fluidized bed suspended solids.
ii absorption of a portion of the dissolved carbonaceous mat-erial ammonia and phosphorus into microbial cells.
iii. adsorption of a portion of soluble phosphates on to surfaces of said fluidized bed solids.
iv. biological respiratory denitrification of nitrite and ni-trate nitrogenous material to nitrogen gas.
v. biological oxidation of a portion of dissolved carbonaceous material and a portion of the non-nitrite and/or non-nitrate nitrogenous material using up the oxygen present in the in-coming waste water and the chemically bound oxygen in said nitrite and/or nitrate nitrogenous material, and vi. hydrolysis of the fluidized bed suspended solids.
g) allowing the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said first reaction zone co-currently to said suspension flow and separating the gases from said suspension at the upper level of the fluidized bed and releasing said gases to atmosphere, h) flowing the mixture of partially purified waste water and the fluid-ized bed solids by gravity from said first reaction zone into said second reaction zone, mixing said mixture in said fluidized bed established in said second reaction zone with fluidized bed solids and with the diffused air injected into the recirculated suspension by said submerged propeller and carrying out in the second reaction zone simultaneously the processes of:
i. bio-oxidation of the remaining dissolved carbonaceous mat-erial present in the partially purified waste water, ii. transformation of remaining non-nitrite and/or non-nitrate nitrogenous material to nitrite and/or nitrate nitrogenous material, iii. partial respiratory degradation of the nitrite and/or nitrate nitrogenous material to nitrogenous gas, iv. chemical precipitation of phosphates and free metal ions from the partially purified waste water by the added dissolved mineral, v. adsorption of a portion of soluble phosphates on the surfaces of the fluidized bed solids, vi. partial bio-oxidation of the carbonaceous material adsorbed on the fluidized bed solids, vii. hydrolysis of a portion of fluidized bed solids, viii. coagulation and flocculation of the colloidal matter present in the partially purified waste water, i) allowing the excess diffused air and the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said second reaction zone co-currently to flow of said suspension and separating the gases from the suspension at the upper level of the fluidized bed and releasing the gases to atmosphere, j) flowing the mixture of partially purified waste water and the fluid-ized bed solids by gravity from said second reaction zone into said third reaction zone, mixing said mixture in said fluidized bed est-ablished in said third reaction zone with the purified waste water and with the fluidized bed solids in absence of dissolved oxygen and carrying out in said third reaction zone simultaneously the processes of:
i) bio-oxidation of the carbonaceous material adsorbed on the surfaces of the fluidized bed solids and bio-oxidation of the carbonaceous material absorbed by the microbial cells, ii) respiratory degradation of the nitrite and/or nitrate nit-rogenous material to nitrogenous gas, iii) bio-oxidation of the dissolved material released into the purified waste water through hydrolysis of said fluidized bed solids, iv) coagulation and flocculation of the colloidal matter present in the fluidized bed, v) separation of the suspended solids from the purified waste water, k) allowing the formed carbon dioxide and nitrogenous gases to rise through the fluidized bed in said third reaction zone co-currently to said suspension flow and separating the gases from the suspension at the upper level of the fluidized bed and releasing the gases to atmosphere, l) flowing the suspended solids separated from the purified waste water in said third reaction zone together with portion of the purified waste water back into said first reaction zone completing the process cycle and flowing the purified waste water out of said third reaction zone for further treatment or disposal.
2. The process of claim 1 wherein charcoal in powdered or granulated form is added into the fluidized bed in said first, second and third reaction zones, said charcoal improving the properties of the fluidized bed solids and enhancing the efficiency of the involved processes.
3. The process of claim 1 wherein a fourth reaction zone separated by vertical partitions from first, second and third reaction zones is formed in said reaction tank, said purified waste water is flowing from said third reaction zone by gravity into said fourth reaction zone, continuously adding into said purified waste water flowing from said third reaction zone into said fourth reaction zone chem-ical oxidizing agent, such as potassium permanganate,or hydrogen peroxide, or chlorine, or their mixture, oxidizing in said fourth reaction zone the remaining impurities and killing simultaneously bacteria and viruses present in the purified waste water by said chemical oxidizing agents, and removing the residual suspended solids by settling and flowing the purified waste water out of said fourth reaction zone for further treatment or disposal or reuse.
4. The process of claim 3 wherein a fifth reaction zone separated by vertical partition from fourth and third reaction zones is formed in said reaction tank, said purified waste water is flowing from said fourth reaction zone by gravity into said fifth reaction zone, said fifth reaction zone containing granular charcoal, said pur-ified waste water being flown through said charcoal, decomposing said remaining oxidizing agents present in the purified waste water in contact with said charcoal and flowing the purified waste water out of said fifth reaction zone for further treatment, reuse or disposal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA275,345A CA1064169A (en) | 1977-04-01 | 1977-04-01 | Process for purification of waste water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA275,345A CA1064169A (en) | 1977-04-01 | 1977-04-01 | Process for purification of waste water |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1064169A true CA1064169A (en) | 1979-10-09 |
Family
ID=4108300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA275,345A Expired CA1064169A (en) | 1977-04-01 | 1977-04-01 | Process for purification of waste water |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1064169A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6117323A (en) * | 1997-03-18 | 2000-09-12 | Haggerty; Ken | Process for the biological treatment of wastewater with periods of biomass starvation |
| CN107176746A (en) * | 2016-03-11 | 2017-09-19 | 浙江国清环保科技有限公司 | A kind of bio-aeration system for administering black and odorous water |
| CN115557607A (en) * | 2022-08-31 | 2023-01-03 | 达斯玛环境科技（北京）有限公司 | Integrated biological reaction tank system and method |
-
1977
- 1977-04-01 CA CA275,345A patent/CA1064169A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6117323A (en) * | 1997-03-18 | 2000-09-12 | Haggerty; Ken | Process for the biological treatment of wastewater with periods of biomass starvation |
| CN107176746A (en) * | 2016-03-11 | 2017-09-19 | 浙江国清环保科技有限公司 | A kind of bio-aeration system for administering black and odorous water |
| CN115557607A (en) * | 2022-08-31 | 2023-01-03 | 达斯玛环境科技（北京）有限公司 | Integrated biological reaction tank system and method |
| CN115557607B (en) * | 2022-08-31 | 2024-02-23 | 达斯玛环境科技（北京）有限公司 | Integrated biological reaction tank system and method |
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