CN113946142A

CN113946142A - Automatic control treatment method for sludge dewatering process of sewage water of tap water plant

Info

Publication number: CN113946142A
Application number: CN202110688455.7A
Authority: CN
Inventors: 郭志刚; 贾建青; 陈玲; 邓雷; 郑莉; 翟作卫; 谢世钊; 郭可莹; 刘晖; 魏琳
Original assignee: Henan Zhongxia Environmental Protection Technology Co ltd
Current assignee: Henan Zhongxia Environmental Protection Technology Co ltd
Priority date: 2021-06-19
Filing date: 2021-06-19
Publication date: 2022-01-18
Anticipated expiration: 2041-06-19
Also published as: CN113946142B

Abstract

The invention discloses a self-control treatment method for a dehydration process of sludge in sewage water of a tap water plant, which is used for treating the sewage water and the sludge concentration of the tap water plant and is characterized by comprising the following operation steps: s1: obtaining the precipitation condition through analyzing the sludge property and a static precipitation test; s2: determining the most suitable medicament type and dosage through medicament tests; s3: the high-efficiency sedimentation concentration tank is adopted, and the high-efficiency sedimentation concentration tank and the inclined plate sedimentation are combined, so that the solid content of sludge in a bottom concentration area is improved, and the sludge directly enters a dehydration process to improve the concentration efficiency; s4: through the floating mud-water separation device, the amount of sludge water entering subsequent equipment is reduced. Through the mode, through the research on the treatment process and the technical equipment, compared with the traditional sludge water treatment process, the optimized process and equipment reduce the occupied area of a water plant, reduce the engineering investment, save the energy consumption, and realize the recovery and the economical utilization of water resources.

Description

Automatic control treatment method for sludge dewatering process of sewage water of tap water plant

Technical Field

The invention relates to a process for treating sludge and sludge from a tap water plant, belongs to the field of environment-friendly water treatment, and particularly relates to a self-control treatment method for a sludge and sludge dewatering process of the tap water plant.

Background

Water resource is an important and irreplaceable resource for human beings, is indispensable in the survival and development process of human beings, and in the research of sludge water treatment and sludge disposal of urban water plants, the following problems are found,

current situation of sludge water treatment in urban waterworks

Most of water sources of urban water plants are taken from surface water bodies such as rivers, lakes and the like, sludge discharge water generated by the water plants mainly comes from sludge discharge water of a sedimentation tank and backwashing water of a filtering tank, and sludge in the sludge discharge water consists of suspended impurities such as silt, humus, algae and the like in raw water and coagulants, coagulant aids and the like added by the water plants, wherein the suspended impurities are the main proportion of the sludge, the humus, the algae and the like. Most of domestic urban waterworks do not treat the sludge water of the waterworks and directly discharge the sludge water into nearby natural water bodies, so that certain pollution is caused to the environment, the harm caused by the sludge water of the waterworks is more serious along with the deterioration of the environment, in addition, the sludge water of the waterworks generally accounts for 4% -7% of the total clean water of the waterworks, and the waste of water resources and the increase of energy consumption are caused by direct discharge.

The sludge treatment of the tap water works in foreign cities and towns starts in the 60 th century and has only a development history of decades. The Japanese issued No. 6 of 1975 sets forth the water pollution prevention and control Law, which stipulates that the water works provided with a sedimentation tank and a filter tank must discharge the drained water after the drained water is treated to meet the water quality discharge standard, and legally stipulates that the water works must carry out the treatment of the drained water. In the end of 1978, the Japanese department of related Art investigated the dewatering of sludge in 363 waterworks that had sewage and sludge treatment systems installed in countries around the world, and the results of the investigation are shown in the table.

Water treatment plant sludge dewatering method questionnaire

As can be seen from the above table, the relatively large scale waterworks in the united states, japan, europe, and the like are generally equipped with relatively sophisticated and highly automated sludge water treatment and sludge disposal facilities, and mechanical dewatering methods such as centrifugal dewatering, pressure filtration dewatering, and the like are more commonly used. The sludge amount of tap water plants in Europe after concentration and dehydration accounts for 70% of the sludge amount of all tap water plants; the amount of sludge concentrated and dehydrated in the water works of Japan accounts for more than 80% of the total amount of sludge in the water works.

The treatment of sludge water and the disposal of sludge from waterworks in towns of our country were formally mentioned in the 80 th century. In 1988, Shexingping has compiled "treatment of sewage and sludge in waterworks" in combination with the data of the United states, Japan, Su Union, England, France, and other countries. The book systematically expounds the types, the amounts and the components of sewage and sludge of the water treatment plant, the treatment methods of the sewage and the sludge, the structures, the design and the management of various structures, the recovery of a flocculating agent in the sludge, the final treatment and the utilization of a dewatered mud cake and the like, and has higher reference value for the just started production wastewater treatment industry of the water treatment plant in China.

In 1996-1998, researchers have carried out a series of experimental researches on the on-site concentration and dehydration of the discharged mud water in a workshop of Mingo waterworks in Shanghai, and the good results are obtained. However, with the development of economy and increasing national environmental protection importance, sludge treatment projects are built in some domestic water plants, and after 21 st century, water plants such as the stone village municipal wet stone water plant, the ninth water plant in beijing, the Min running water plant in Shanghai, the Shenzhenmelin water plant, the Guangzhou west water plant, the New Water works in Tianjin, the Daqing Zhongzhui Water plant and the Shenzhenzhu Water plant are continuously built and put into operation, but the proportion of the water plants built with the sludge water treatment devices in the national water plants is still very low. The design standard of outdoor water supply (GB 50013-2006) increases the content of treatment of the sludge water of the water treatment plant, clearly defines the process flow of the treatment of the sludge water of the water treatment plant, sludge regulation, concentration, dehydration, sludge cake disposal, utilization and the like, and defines that the water quality of the natural water bodies discharged into rivers, ditches and the like after the treatment of the sludge water of the water treatment plant conforms to the current national standard of comprehensive wastewater discharge standard.

At present, other clear specifications and design standards do not exist in the sludge treatment engineering of the urban waterworks at home, and since now, sludge treatment facilities are built in the urban waterworks in China, so that the key technology and equipment for researching the efficient treatment of the sludge water of the urban waterworks and saving water resources are very necessary.

The main problems of the (II) sludge water treatment technology

(1) The process is immature

The existing facilities for treating the sludge water of the tap water plant are not enough to research the generation path and the physical and chemical properties of the sludge water of the tap water plant, so that the municipal sewage and sludge treatment method is designed and applied to a great extent, and the process cannot be reasonably considered by combining the characteristics of the tap water plant.

2) Large occupied area

The existing sludge water treatment facilities of tap water plants, such as delay water plants in Taiyuan city, can treat water with the amount of 40 ten thousand meters³(d) floor area 3400m²(ii) a The water treatment quantity of the Lingzhuang water plant is 75 ten thousand meters³D, floor area 9600m²(ii) a Water treatment capacity of 50 km in Guangdong water works³D, floor area 4000m². The occupied area is 80-128m based on the unit water yield²Ten thousand meters³. For the established waterworks in towns, the site for sludge water treatment is not reserved in the original design, and if a sludge water treatment facility is newly built, the site can not meet the requirements.

(3) High operation cost and incapability of realizing full-automatic control during operation

As the conventional process does not fully consider the reduction and recovery of sludge water, the system is arranged and configured in a large scale, and the corresponding operation energy consumption and the addition amount of the medicament are large. When the sludge dewatering system is designed, automatic control cannot be realized, an operator must monitor the sludge in the whole process during operation, and the labor intensity of the operator is high.

Purpose and significance of (III) project research

(1) Need for water conservation

China is a country with abundant total water resources, and the total water resources in the whole country in 2014 are 27266.9 hundred million m³And 6 th bit in the world. However, the per-capitalized occupancy of China is about 2200 m³1/4, the world's average level only, is one of the 13 water-poor countries in the world.

According to the production process of the waterworks, the waterworks sludge is mainly derived from production drainage and production sludge. The production drainage is from the back flushing drainage of the filter tank, and the production drainage is generated by the drainage of the reaction sedimentation tank. The back flushing sludge discharge amount of the filter is large (about 3.5-5% of the water yield), the water content of the sludge is high (about 99.9%), most of the sludge can flow back and less sludge can be deposited if the sludge is concentrated in the drainage tank after standing; the sludge discharge water of the sedimentation tank accounts for about 1.5 to 2 percent of the water yield, and the water content is relatively low (about 99.7 percent). The total sludge water generally accounts for 4% -7% of the total clean water of the water plant, and the direct discharge mode causes waste of water resources and increase of energy consumption.

(2) Need for environmental protection

Although sludge treatment has been in development history for over a hundred years, sludge treatment in waterworks has been in development history for only a few decades. The reason is that the sludge of the water plant is essentially different from the traditional sludge, the sludge of the water plant mainly comes from the sludge discharge of a sedimentation tank and the back flushing wastewater of a filter tank of the water plant, and the components of the sludge mainly depend on the water quality of a water source of the water plant and added medicaments. In water plants using rivers and rivers as water sources, the sludge mainly contains silt due to the large content of silt in the source water; in a water plant using lake water as a water source, the source water has good water quality and low silt content, and the sludge mainly comprises the following components: plankton, flocculant substances, organic matters, metal hydroxides (such as a small amount of iron and manganese compounds) and substances added during treatment. The direct discharge of a large amount of untreated sludge water can cause the following harm to the environment:

(1) After a large amount of silt and suspended matters in the discharged muddy water of the water works enter the water body, silt can be deposited, and the original hydraulic conditions of the water body are changed.

(2) The discharged water body is polluted by a large amount of pollutants such as suspended matters, organic matters and the like contained in the sludge water of the waterworks. According to the estimation, the dry sludge amount generated by all water plants in Shanghai cities is over 13.3 million tons every year, the organic matters are over 1.3 million tons, and the impact on the environment is obvious.

(3) At present, most of tap factories adopt aluminum salt as a coagulant, and a large amount of aluminum sludge is discharged into a water body and can damage aquatic organisms and benthic organisms, so that the ecological balance of the water body is damaged.

With the development of economy and the increasing importance of the country on environmental protection, the mode of directly discharging the sludge in the waterworks without treatment is more and more emphasized by governments, industries and people, particularly, some waterworks directly discharge the sludge water to the urban landscape water body have serious water body pollution, and some waterworks have received the correction notice issued by the environmental protection department.

The 'design code for outdoor water supply' (GB 50013-2006) issued by the nation in 2006 increases the content of sludge water treatment in water treatment plants, and requires that corresponding sludge water treatment facilities must be built in new waterworks. The traditional sludge water process of the waterworks adopts sludge collection, an advection type sedimentation tank, a mechanical stirring clarification tank and dehydration treatment, has the problems of large occupied area, high investment cost, high operating cost and the like, and partial newly-built waterworks are not provided with corresponding sludge water treatment measures, so that the existing waterworks are limited by sites and cannot be provided with sludge water treatment facilities.

In conclusion, the research of the project aims to research a key technology and equipment for efficient treatment of the sludge water and water resource saving of the urban tap water plant, which is small in occupied area, low in investment cost and low in operating cost.

Disclosure of Invention

The invention mainly solves the technical problem of how to provide a self-control treatment method for the sludge dewatering process of the waterworks, which reduces the land occupation of the waterworks, reduces the engineering investment, saves the energy consumption, and realizes the water resource recovery and the economical utilization.

In order to solve the technical problems, the invention adopts a technical scheme that: the automatic control treatment method of the sludge dewatering process of the sludge discharged from the tap water plant is used for treating the sludge discharged from the tap water plant and concentrating the sludge, and comprises the following operation steps:

s1: obtaining the precipitation condition through analyzing the sludge property and a static precipitation test;

s2: determining the most suitable medicament type and dosage through medicament tests;

s3: the high-efficiency sedimentation concentration tank is adopted, and the high-efficiency sedimentation concentration tank and the inclined plate sedimentation are combined, so that the solid content of sludge in a bottom concentration area is improved, and the sludge directly enters a dehydration process to improve the concentration efficiency;

s4: through the floating mud-water separation device, the amount of sludge water entering subsequent equipment is reduced.

In a preferred embodiment, step S1 includes the following steps of analyzing the properties of the sludge and performing a static sedimentation test, including the following steps:

SS 1: measuring the settling performance and solid content of the sludge;

SS 2: judging the properties of the sludge;

in the step SS1, the sedimentation performance of the sludge is measured by drawing a sedimentation curve, and a compression point and a limit solid flux are obtained through the sedimentation curve.

In a preferred embodiment, the specific operation steps of the settling curve in step SS1 are:

firstly, making a settlement curve according to a static settlement test of sludge;

secondly, making two tangent lines of the constant-speed sedimentation area and the compression area, making an angle bisector by the intersection angle of the two tangent lines, and making the intersection point of the angle bisector and the sedimentation curve as a compression point;

thirdly, drawing a tangent line of the settlement curve through the compression point;

cutting on the ordinate axis to reach sludge discharge concentration C_uInterfacial height of sludge_uMaking parallel line of abscissa, intersecting with tangent line passing through compression point, and the abscissa value of the intersection point is tu;

fifthly, if the sedimentation curve has no constant-speed sedimentation area, the constant-speed sedimentation curve enters a compression area at the beginning, the constant-speed sedimentation curve intersects with the sedimentation curve through a parallel line taking Hu as an abscissa, and the abscissa corresponding to the intersection point is tu;

Sixthly, solving tu by using a graphical method, and then substituting the tu into a formula to obtain the limit solid flux G;

。

in a preferred embodiment, the specific operation steps of the determination of the solid content in the step SS1 are to determine by using a calculation formula of the water content of the sludge and a calculation formula of the solid content of the sludge,

the calculation formula of the water content of the sludge is as follows:

wherein, A: calculating the water content of the sludge, B: calculating the solid content of the sludge;

the calculation formula of the solid content of the sludge is as follows:

，

wherein: pw: water content (%) of sludge; p: the solid content of the sludge; w: water weight (g) in sludge; s: total solids weight (g) in sludge.

In a preferred embodiment, the step of determining the nature of the sludge in step SS2 comprises:

firstly, measuring the solid content of the sludge;

measuring the sludge dewatering performance;

measuring the properties of sludge alum floc;

fourthly, analyzing the influence of the particle size distribution on the sludge dewatering property;

analyzing the influence of the density of alum blossom on the sludge dewatering property;

sixthly, determining and analyzing the influence of compressibility and compressibility on the dehydration rate and the shear strength.

In a preferred embodiment, in the step of measuring the solid content of the sludge, impurities in the water and the sludge are combined together for adsorption and are electrically neutralized.

In a preferred embodiment, the dehydration performance of the sludge in the step (II) is generally expressed by specific resistance, and the smaller the specific resistance, the better the dehydration performance of the sludge. Specific resistance is defined as the resistance per unit dry solids weight of filter cake per unit filtration area;

the formula of the specific resistance is as follows:

r: specific resistance of sludge, (m/kg);

b: slope of t/V vs. V curve, (s/m)⁶）；

A: filtration area, (m)²)；

P: pressure (Pa):

c: weight of sludge cake produced per unit volume of filtrate, (kg/m)³)；

W_b: dry sludge weight, (kg);

V_f: volume of filtrate, (m)³)；

: viscosity coefficient (Pa · s).

In a preferred embodiment, step two:

when the specific resistance is less than or equal to 10X10¹⁰When m/kg, the performance is judged to be good;

when the specific resistance is more than 100X10¹¹At m/kg, the sludge dewatering performance is poor.

In a preferred embodiment, the influence of the particle size distribution on the sludge dewatering property is analyzed in step (iv) by using a low osmotic pressure gradient medium to measure the density of alum flocs.

In a preferred embodiment, in the operation step of compressibility, the dehydration rate is decreased when the pressure is increased in the dehydration process, and the compressibility of the sludge is expressed by the following formula:

r₁: at a pressure P₁Specific resistance of time

r₂: at a pressure P ₂Specific resistance of time

S: coefficient of compression

The compressibility S is generally obtained in a step with a specific resistance r and a pressure P,

wherein: the S value is about 0.8 to 1.5.

In a preferred embodiment, in step S2, the cationic PAM is screened out according to step S1, and three helical blade pipeline mixing devices are used, and the water flow passes through the pipeline mixer to generate diversion, cross mixing and reverse rotational flow, so that the added medicament is rapidly and uniformly diffused into the whole water body, thereby achieving instantaneous mixing.

In a preferred embodiment, in step S3, a high efficiency precipitation concentration tank is used, which is composed of three parts, i.e., a reaction zone, a concentration zone and a precipitation separation zone.

In a preferred embodiment, the method comprises the following steps:

(1) setting the circulation mode as reaction area circulation, wherein the reaction mode is internal circulation, and fully reacting the medicament, the water and the sludge in the step S2;

(2) the sludge is internally refluxed and the refluxed sludge is used as a condensation nucleus of flocculation reaction, so that the floc is more compact;

(3) the umbrella-shaped inclined plate filler based on the shallow pool principle greatly increases the surface area of the precipitation separation area, thereby improving the separation effect;

(4) and the organic polymer flocculant is adopted to accelerate the forming of flocs and reduce the flocculation reaction time.

In a preferred embodiment, in the step (4), the sedimentation speed of the sludge is increased and the volume required by sludge concentration is reduced through the synergistic effect of flocculation cores, polymer bridging and particle collision.

The invention has the beneficial effects that: through research on the treatment process and technical equipment, compared with the traditional sludge water treatment process, the optimized process and equipment reduce the occupied area of a water plant, reduce the engineering investment, save the energy consumption, and realize the recovery and the saving utilization of water resources.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a settling curve diagram of the self-control treatment method of the sludge dewatering process of the effluent water plant of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a self-control treatment method for a sludge dewatering process of sewage sludge in a tap water plant in a specific embodiment.

Example 1

The automatic control treatment method of the sludge dewatering process of the sludge discharged from the tap water plant is used for treating the sludge discharged from the tap water plant and concentrating the sludge, and comprises the following operation steps:

SS 1: measuring the settling performance and solid content of the sludge;

SS 2: judging the properties of the sludge;

。

The calculation formula of the water content of the sludge is as follows:

the calculation formula of the solid content of the sludge is as follows:

，

firstly, measuring the solid content of the sludge;

measuring the sludge dewatering performance;

measuring the properties of sludge alum floc;

The formula of the specific resistance is as follows:

r: specific resistance of sludge, (m/kg);

b: slope of t/V vs. V curve, (s/m)⁶）；

A: filtration area, (m)²)；

P: pressure (Pa):

c: weight of sludge cake produced per unit volume of filtrate, (kg/m)³)；

W_b: dry sludge weight, (kg);

V_f: volume of filtrate, (m)³)；

: viscosity coefficient (Pa · s).

In a preferred embodiment, step two:

r₁: at a pressure P₁Specific resistance of time

r₂: at a pressure P₂Specific resistance of time

S: coefficient of compression

wherein: the S value is about 0.8 to 1.5.

In a preferred embodiment, the method comprises the following steps:

Example 2

A self-control treatment method for a sludge dewatering process of sludge discharged from a tap water plant is used for treating sludge discharged from the tap water plant and concentrating the sludge, and comprises the following operation steps:

(1) Through the analytical research to concentrator, confirm to adopt high-efficient sediment concentration tank to replace traditional sludge thickener to reduce the water purification plant and take up an area of, improve concentration efficiency.

In order to solve the problems that the traditional process occupies a large area, adapts to the construction of the existing water plant, particularly the reconstruction requirement of the built water plant, and has very strict requirements on the occupied area of the selected process. The concentration tank is a key structure for the success or failure of sludge treatment, and because the sludge generated by waterworks using surface water as a water source is not easy to concentrate, if the traditional gravity type sludge concentration tank is adopted, the surface load of the concentration tank must be reduced to be very low, so that the occupied area of the concentration tank is large, and the concentration effect is poor. Therefore, the project adopts the high-efficiency sedimentation concentration tank as the sludge concentration tank and combines the inclined plate sedimentation principle to replace the traditional gravity type concentration tank.

(2) Through the test of the medicament, the most suitable medicament type and dosage are determined, and the best treatment effect is achieved.

Since a large amount of inorganic flocculants such as polyaluminium chloride and the like are added in the raw water treatment process of the water works, the inorganic flocculants in the discharged muddy water are in a saturated state, and the inorganic flocculants such as polyaluminium chloride or polyferric sulfate and the like are added, so that the sludge sedimentation of the discharged muddy water cannot be promoted. At present, polyacrylamide is a common organic polymeric flocculant in sludge water treatment, and can be divided into 3 types of cations, anions and non-ions according to charges of polyacrylamide, and the most appropriate type and dosage of the flocculant are determined through research.

(3) The optimum condition of sedimentation is researched by analyzing the sludge property and a laboratory static sedimentation test.

Waterworks sludge contains various kinds of moisture, their existing states are different, surface activity is extremely complicated, and the sludge has moisture of 4 types: free water, alum flower water, capillary water and bound water, wherein the existing forms, properties and settling properties of the water in all states are different, and the optimal conditions of precipitation are researched through experiments.

(4) The research on how to reduce the engineering floor area and the equipment energy consumption by a floating type mud-water separation device.

The regulating tank with continuous flowing water inlet is adopted, the water quantity is often buffered by a larger tank capacity, and the operation effect is poorer; adopt the equalizing basin of intermittent type nature into water, need the longer turbidity that just can guarantee above the outlet of static settling time to satisfy the retrieval and utilization requirement, often arrange to the water pump of great specification in order to shorten drainage time for the running cost is high, and degree of automation is poor, and reuse water quality of water fluctuates greatly. The floating type mud-water separation device can completely separate drainage time and sludge settling time, so that not only is the addition of medicaments saved and the cost reduced and the increase of sludge amount reduced, but also the important thing is that the amount of sludge water entering subsequent equipment is reduced, the design load and the operation load of the subsequent equipment are greatly reduced, and the reduction of occupied area and the great reduction of operation energy consumption are realized.

In the study of the properties of the sludge, the following operational aspects were included:

and (I) measuring the settling performance and the solid content of the sludge.

The sludge settling property mainly comprises natural settling characteristics of sludge water with different solid contents, compacted solid flux of the sludge water and concentration time required by subsequent dehydration treatment.

(1) Settling curve:

and (3) a sedimentation tank sludge water static sedimentation characteristic curve made by a 1000 mL measuring cylinder. It can be seen that the sedimentation rate of the muddy liquid surface is continuously reduced along with the increase of time in the static sedimentation process of the sludge in the discharged muddy water, and the sedimentation characteristics of the sludge with different solid contents are obviously different. When the solid content is low, the sludge can quickly form a settlement surface in the initial stage, the settlement is quick, the sludge reaches a compaction point quickly, and the settlement curve is obviously turned near the compaction point. Along with the increase of the solid content of the discharged sludge water, the time for forming a settling surface by the sludge is correspondingly prolonged, the constant-speed settling process in the initial stage is not obvious, the settling rate of the sludge interface is slower and slower, the curve gradually tends to be gentle after the sludge interface is used, and the compaction point is not obvious. This is mainly because: at low solid content, particles in the muddy water interfere with colony sedimentation. The sedimentation rule is that the floc particles are increased due to the self-flocculation of the particles at first, so that the sedimentation speed is accelerated. But simultaneously, the resistance born by the sinking particles is correspondingly increased due to the increase of the flow velocity of the relative ascending water flow, and a stress balance condition is quickly achieved. At this time, the muddy liquid level enters the equal-speed sedimentation stage. Along with the proceeding of sedimentation, the concentration of particles in the muddy water is increased along the sedimentation direction of the particles, and the particles are subjected to integral compression sedimentation. At this time, the mud water floc particles are further close to and mutually contact, and the molecular force action between the particles is more obvious and strengthened. The network of flocks occurs quickly and will form a network of whole bodies in a relatively short time. Meanwhile, due to the sharp increase of the ultimate shear stress in the water body, the relative motion of the floc particles is gradually weakened or even disappears, so that the particles with different sizes sink in an integral form, and the separation and the relative motion of the particles do not exist. The appearance is that the sinking speed of the muddy liquid surface is further reduced.

The compression point and the limit solid flux can be calculated through a settlement curve, and the specific method is as follows:

making two tangent lines of the constant-speed sedimentation area and the compression area, making an angle bisector by the intersection angle of the two tangent lines, and obtaining the intersection point of the angle bisector and the sedimentation curve, namely the compression point;

drawing a tangent line of the settlement curve through the compression point;

cutting on the ordinate axis to reach sludge discharge concentration C_uInterfacial height of sludge_u，(H_uCan be according to Kynch formula C₀H₀ =C_uH_uCalculated), making a parallel line of the abscissa, intersecting with a tangent line passing through the compression point, and the abscissa value of the intersection point is tu;

if the sedimentation curve has no constant-speed sedimentation region, the curve enters a compression region from the beginning, the curve crosses the sedimentation curve by using Hu as a parallel line of an abscissa, and the abscissa corresponding to the crossing point is tu;

sixthly, solving tu by a graphical method, and then substituting the tu into a formula to obtain the limit solid flux G.

(2) Water content and solid content of sludge

The amount of water contained in the sludge is called the water content, and the water content of the sludge is expressed by the water content, namely the weight percentage of the water contained in the unit weight of the sludge.

The water content of the sludge can be calculated by the following formula:

pw: sludge moisture content (%)

W: water weight (g) in sludge

S: total solids weight (g) in sludge

The solid content of the sludge can be calculated by the following formula:

ps: the solid content of the sludge is%

S: total solids weight (g) in sludge

W: water weight (g) in sludge

(II) Properties of the sludge

1. Solid content of sludge

Moisture in sludge: waterworks sludge contains various water contents, and their existing states are different, and the surface activity is extremely complicated. There are many classifications of water in sludge, and the waste forest (Vesilind) classifies the water in sludge into 4 types: (1) free water, which exists between particles, is less subject to surface tension or capillary action and can be removed by simple gravity concentration; (2) alum blossom water is caught in sludge alum blossom through a net and can be removed through mechanical dehydration; (3) capillary water, namely capillary water among sludge particles, is relatively large in surface tension or capillary action, is not easy to lose under the action of gravity, and can be removed only through extrusion and deformation of the sludge particles; (4) the combined water is water chemically combined by alum blossom particles. Of the water contents of the sludge, free water is most easily removed and can be removed only by simple gravity concentration or mechanical dehydration, and bound water is most difficult to remove, and the sludge cake can be partially removed by heating drying or incineration treatment. Chemical agents (organic high molecular polymers, acid, alkali and the like) are added for pretreatment or freezing-unfreezing pretreatment, so that the form of partial alum flower water or capillary water can be changed into free water which is easy to lose. The content of various moisture in the sludge directly affects the solid content of the sludge after the sludge is concentrated and dewatered, so that the understanding of the moisture content is very important.

Factors affecting solid content change: the change range of the solid content of the sludge in the waterworks is usually large, which is mainly determined by the nature of raw water, the type and the adding amount of a coagulant, whether lime is used or not, and the like. Generally, the higher the suspended solids and calcium carbonate content, the higher the solids content of the sludge. Therefore, when the turbidity of the raw water is low, the solid content of the sludge is low, and when the turbidity of the raw water is high, the solid content of the sludge is high. The study by Knocke et al showed that: the turbidity of raw water, the addition amount of a coagulant and the coagulation mechanism have great influence on the concentration and dehydration properties of sludge. When the pH value of the coagulation is 8.1, the solid content of the mud cake after the mud water concentration and dehydration is much lower than that of the mud cake with the pH value of 6.2; the solid content of the sludge when the adding amount of the aluminum sulfate is high is obviously lower than that when the adding amount of the aluminum sulfate is low; from the coagulation mechanism, the solid content of the sludge generated by net capture is lower than that generated by adsorption-electric neutralization. Therefore, it is most desirable to perform an adsorption-electrical neutralization treatment in which impurities in water are combined with sludge, and not only the amount of aluminum salt used is small, but also the proportion of suspended particles in the sludge is high, the proportion of aluminum hydroxide is low, and the sludge is easily dehydrated. Thus, when considering the selection of coagulation conditions, the following should be noted: (1) reducing the pH value during coagulation; (2) reducing the ratio of the coagulant dosage to the water inlet turbidity; (3) the coagulation mechanism should be controlled to adsorption-electric neutralization.

2. Specific resistance

The sludge dewatering performance is generally expressed by specific resistance, and the smaller the specific resistance, the better the sludge dewatering performance. Specific resistance is defined as the resistance per unit dry solids weight of filter cake per unit area of filtration. The formula of the specific resistance is shown as follows:

r: specific resistance of sludge, (m/kg);

b: slope of t/V vs. V curve, (s/m)⁶）；

A: filtration area, (m)²)；

P: pressure (Pa):

c: weight of sludge cake produced per unit volume of filtrate, (kg/m)³)；

W_b: dry sludge weight, (kg);

V_f: volume of filtrate, (m)³)；

: viscosity coefficient (Pa · s).

The specific resistance varies widely, and is generally considered to be 10X10 or less¹⁰The sludge with m/kg is easy to dehydrate, and when the specific resistance is more than 100X10¹¹At m/kg, the sludge dewatering performance is poor. The specific resistance of the coagulant sludge increases with increasing pH and decreases with increasing raw water turbidity. In the coagulation process, if the water content in the sludge alum floc is higher, the dehydration speed is slow, the dehydration speed of the aluminum hydroxide sludge generated by low-turbidity raw water is slow, and the solid content of the dehydrated sludge cake is low.

3. Properties of sludge alum floc

The properties of alum floc, such as particle size distribution and alum floc density, have great influence on sludge concentration, dehydration rate and dehydration degree.

4. Particle size distribution

The geometrical shape of sludge alum flocs generated in the water treatment process is extremely irregular and disordered, and thus is difficult to describe. Some studies generally analyze sludge particles as spheres, but the error is large. Knocke et al, when observing the sludge alum by a microscope, consider that most of the sludge particles are more nearly elliptical, and measure that the ratio of the length of the major axis to the minor axis of the sludge particles is about 0.5 to 0.75. In recent years, some researches describe the structure of sludge flocs, sludge alum floc characteristics and filter mud cake characteristics by using an irregular fragment theory with no definite form or disorder mathematically, and describe the effective density of the irregular fragments (

) Expressed as n radii R₀The primary particle of (a) an irregular chip-to-ratio (c) having a radius of R and a density of a primary particle of (b)

) See formula:

the irregular fragment size D can be obtained by the slope of a double logarithmic curve of the diameter and the effective alum floc density, the theoretical value of the irregular fragment size is 1-3, and the content of the combined water in the sludge alum floc is remarkably reduced along with the increase of the irregular fragment size through research, and the irregular fragment size D and the effective alum floc density are in a very obvious linear relationship.

There have been many studies on the influence of the particle size distribution on the sludge dewatering property, and there are studies that the particle size distribution has a great influence on the sludge dewatering, and the specific resistance of the sludge decreases with the increase of the sludge size particles, and the sludge dewatering property improves accordingly. Because of the influence of factors such as the height irregularity of sludge particles, a measuring method and the like, the influence degree of the particle size distribution on the sludge dewatering property is not determined at present, and more detailed research is needed.

5. Density of alumen ustum

The density of alum floc is another important factor affecting the sludge dewatering property. The influence of the density of alum flocs on the dehydration effect is considered to be more important than the influence of the particle size distribution of alum flocs, and in the research of concentration and various mechanical dehydration, the close relationship between the density of alum flocs and the solid content of dehydrated mud cakes is obtained. With the increase of density of alum floc, the solid content of the sludge after concentration and dehydration is increased.

As the suspended solids (kaolin) in the alum flocs increase, the density of the alum flocs increases, the solid content of the sludge cake after sedimentation and dehydration also increases, and the influence of organic matters on the alum flocs density is considered to be reduced along with the increase of the content of the organic matters in the alum flocs, and the dehydration rate and the solid content of the sludge cake after dehydration are both reduced. Different reports about the density of alum flocs of the aluminum sludge are related to the test method and the content of organic matters (TOC) in the sludge, and the alum floc density of the aluminum sludge is found to be in a range of 1.14-1.22.

There are many methods for measuring density of alum flocs, but it is generally considered that the density of alum flocs measured by using low-osmotic pressure gradient medium is more reasonable than other commonly used methods (such as sucrose method). The use of high osmotic pressure media may result in higher density values than the actual values, since high osmotic pressure will cause water to flow out of the sludge flocs during the measurement.

6. Compressibility

Compressibility is considered to be a result of distortion of alum flocs during dewatering, and most of the coagulant-added waterworks sludge has high compressibility. The main consequence of compressibility is that the rate of dewatering decreases as the pressure increases in the dewatering process.

The compressibility of sludge is generally expressed by the formula:

r₁: at a pressure P₁Specific resistance of time

r₂: at a pressure P₂Specific resistance of time

S: coefficient of compression

The compressibility factor S is usually determined from a log-log plot of the specific resistance r and the pressure P. For conventional sludge, the S value is about 0.8-1.5; the S-value of the softened sludge can be reduced to 0.4, since the sludge is mainly composed of calcium carbonate. Many tests have shown that sludge under pressure causes deformation, which increases the filtration resistance.

The compressibility of the aluminum sludge is approximately equal to 1.0 and the compressibility of the lime sludge is slightly lower, indicating that the lime sludge is slightly less compressible than the aluminum sludge. The change of density of the alum flocs does not greatly influence the compressibility, and the change of particle size does not influence the compressibility of the sludge.

For low turbidity raw water, the content of hydroxide in the sludge generated is generally high, and when pressure is applied, the dehydration performance of the sludge is poor; in contrast, with sludge containing a large amount of inert particles, the dewatering performance does not deteriorate significantly when pressure is applied. This is mainly due to the effect of sludge compressibility, which should be taken into account when designing sludge dewatering systems.

7. Shear strength

Shear strength is an important property affecting sludge disposability, and is critical, especially in designing and analyzing sludge land-fill stability. Traditionally, the solid content of dewatered sludge is taken as a method for measuring the sludge treatment and final treatment properties, but researches show that the sludge with the solid content in a wide range has similar treatment properties, and the sludge disposability cannot be directly judged only by the solid content of a sludge cake. The shearing strength of the Sichuan clay cake reaches 292-390kg/m²(0.02-0.05tons/ft²) And the sludge treatment requirement can be met. According to the range of the shear strength requirement, for the aluminum sludge, the treatment requirement is met when the solid content is 15-20%, and some lime softening sludge may need more than 50% of the solid content to meet the treatment requirement.

In one embodiment, the apparatus includes a floating mud-water separation device.

According to the treatment process of a tap water plant, sludge mainly comes from filter backwashing drainage and reaction sedimentation tank sludge drainage, main solids in filter backwashing wastewater are fine alumen ustum and flocculent objects crushed in a flocculation sedimentation process, the contained solids are about 0.04 percent generally, and the sedimentation performance is poor; the main solid of the sludge discharged from the sedimentation tank is a flocculation sedimentation product, and the sludge in the sedimentation tank is compressed, so that the solid content is higher, generally between 0.5 and 1 percent, the particle geometric size is larger, and the sedimentation and the separation are easy. According to the water quality conditions of the back flushing water of the filter tank and the sludge discharging water of the sedimentation tank, the traditional adjusting tank can be roughly divided into the following two forms:

the formula of the separate construction: the backwashing wastewater adjusting tank and the sludge discharge water adjusting tank can be independently arranged, the sludge concentration of the two types of wastewater which are independently treated and conveyed to the concentration process is higher, but the structure is more complex, the occupied area is larger, the equipment is more, and the manufacturing cost is high.

The joint building formula is as follows: the two kinds of waste water are merged in the same pool for treatment, although the sludge concentration conveyed to the concentration process is slightly low, the structure is simple, the occupied area is small, the equipment is few, and the cost is low.

The advantage and disadvantage of combining two kinds of forms of traditional equalizing basin has developed floating mud-water separation equipment, through floating mud-water separation equipment for original equalizing basin function is diversified, not only can regulating pondage and quality of water, can also play the concentrated effect of mud, realizes the purpose of multistage concentrated decrement, has solved the problem that original build-together equalizing basin mud concentration is low, follow-up mud concentrated pond concentration effect is poor and bulky.

Working principle of floating type mud-water separation device

Scientifically and reasonably setting the sludge discharge time of the reaction sedimentation tank and the back flush time of the filter tank, discharging the back flush water discharged by the filter tank and the sludge discharged by the reaction sedimentation tank into a combined type regulating tank in a certain time period, and enabling the regulating tank to enter a static sedimentation process after the water discharge is finished; the static sedimentation time is determined through the early-stage analysis and experiments of the field water quality, when the turbidity index of the surface layer clear water meets the recycling requirement, the floating type mud-water separation device starts to work, the surface layer clear water is collected by the floating type mud-water separation device and then is conveyed into a water inlet adjusting tank of a water plant, the floating type mud-water separation device automatically descends along with the descending of the water level, and the surface layer clear water is always discharged by the floating type mud-water separation device in the process, so that the water quality entering the water inlet adjusting tank of the water plant is ensured; when a large amount of surface clear water is discharged and the water level is reduced to a certain degree, and the turbidity index of the surface clear water cannot meet the recycling requirement, the floating type mud-water separation device stops working, a mud scraper, a stirrer and a sludge lifting pump in the adjusting tank start working, and the concentrated sludge is conveyed to a subsequent link.

The research on the effect of the static precipitation treatment of the sludge discharge water comprises the following steps:

1. test method

The mixed sludge water is obtained from a comprehensive adjusting tank of a certain water plant and is conveyed to a settling column by a submersible pump for static settling test. Taking four groups of different water samples, respectively taking supernate in 0, 0.5, 1, 2 and 4 hours, detecting the turbidity of the supernate, and researching the influence of hydraulic retention time on the quality of the supernate.

2. Testing device

The settling column adopts an acrylic organic glass column with the diameter of 250 mm and the height of 1650 mm, a 1000ml beaker and the like.

3. Test results and analysis

Static precipitation treatment tests were performed on the four groups of mixed sludge water, and specific experimental data are shown in the following table.

Through the analysis of the analyzed data, the turbidity change is obvious in the time period from 0h to 0.5h of the settling time, and after the time exceeds 0.5h, the turbidity change of the supernatant is not obviously different from the ratio of 0.5h along with the continuous extension of the time, and the turbidity of the supernatant is gradually stable. The turbidity of the muddy water with different turbidity shows a descending trend along with the change of time, the sedimentation performance of the muddy water with different turbidity is slightly different, the turbidity of 4 groups of water samples tends to be stable after standing and settling for 0.5h, and the change of the continuous sedimentation turbidity is smaller.

The layered drainage mode is used for researching the static sedimentation treatment effect of the discharged muddy water:

1. Test method

The mixed sludge water is obtained from a comprehensive adjusting tank of a certain water plant and is conveyed to a settling column by a submersible pump for static settling test. Taking the same group of water samples at 1#, 2#, 3# and 4# sampling ports respectively, taking supernate at different times of 0, 0.5, 1, 2 and 4h, detecting the turbidity of the supernate, and researching the influence of hydraulic retention time on water quality at different liquid levels.

2. Testing device

The settling column adopts an acrylic organic glass column with the diameter of 250 mm and the height of 1650 mm, and is the same as a test device in 1.2.2, a 1000ml beaker and the like.

3. Test results and analysis

The static sedimentation treatment tests of the same group of mixed sludge water and different liquid levels and depths at different times are carried out, and specific experimental data are shown in the following table.

Through the analysis of the analyzed data, the turbidity change of the water quality at different liquid levels is obvious along with the time period from 0h to 0.5h of sedimentation time; after exceeding 0.5h, the water quality change at different liquid levels and the ratio of 0.5h continue to be prolonged along with the time, although the change is not obvious, the turbidity still is in a descending trend, the water quality of the 2# sampling port is close to the 0.5h water quality level of the 1# sampling port in 1h, the water quality of the 3# sampling port is close to the 0.5h water quality level of the 1# sampling port in 2h, and the water quality of the 3# sampling port is close to the 0.5h water quality level of the 1# sampling port in 4h, so that the water quality is different.

In the analysis of the static sedimentation treatment effect of the discharged muddy water by the floating muddy water separation device, a regulating tank for continuous flowing water inlet is adopted, and in the operation process, as the fluctuation of the water volume of the incoming water is large, in order to reduce the impact on the sludge deposited in the regulating tank, the water volume is often buffered by a large tank capacity, and the operation effect is poor; and adopt the equalizing basin of intermittent type nature into water, at this operation in-process, the drainage mode is fixed drainage, needs the longer turbidity that just can guarantee above the outlet of static settling time to satisfy the retrieval and utilization requirement, often arranges the water pump to great specification in order to shorten drainage time for the running cost is high, and degree of automation is poor, and the quality of reuse water is undulant greatly.

The floating type mud-water separation device can completely separate drainage time and sludge sedimentation time, and the supernatant water quality of the regulating tank is monitored in real time by an automatic monitoring system, so that the floating type mud-water separation device is automatically started when the requirement of reuse water is met; along with the reduction of the water level, the floating type mud-water separation device also reduces, which is favorable for ensuring that the water discharged out of the regulating tank is always supernatant fluid and avoiding the fluctuation of the quality of the reuse water; when the sewage is discharged to the position near the lower sludge enrichment area, the floating type mud-water separation device stops working. The static sedimentation mode does not need adding medicaments, so that the cost is saved, and the sludge water is not added with medicaments, thereby avoiding the further pollution of the sludge water and reducing the increase of the sludge amount. The floating type mud-water separation device greatly shortens the time required by the static sedimentation and drainage of the adjusting tank, can effectively reduce the tank capacity of the traditional adjusting tank, reduces the occupied area of the adjusting tank and improves the automation degree of the whole mud-water treatment; particularly, for waterworks without sludge water treatment facilities, the available area in the factory is limited, the problem of land shortage of sludge water treatment facilities can be better solved by adopting the floating type sludge water separation device and the co-building type regulating tank, and the device has higher economic value and social benefit.

In the research process of the high-efficiency concentration device:

in the whole sludge water discharging process of a water works, the sludge water discharging concentration process occupies a very important position, the concentration of the bottom flow of the concentration tank directly influences the sludge dewatering effect, the cost of the whole process is determined, and the economic benefit of enterprises is related. The sludge concentration process can adopt gravity concentration, air flotation concentration, centrifugal concentration, hydraulic cyclone concentration and the like. The gravity concentration is more applied to the sludge concentration of the waterworks and is preferentially adopted under the condition of land permission because of simple structure, convenient management, excellent concentration effect and low manufacturing cost, and is more suitable for the sludge property of the waterworks.

The traditional continuous flow gravity concentration tank is mainly divided into a vertical flow type and a radial flow type. The vertical flow type mainly adopts an inclined tube (plate) concentration tank, has high concentration efficiency and small occupied area, but has poor regulating capacity, and the capacity is not enough to be regulated when the higher turbidity of raw water is treated. The radial-flow concentration tank has three regions, namely an upper clarification region, a middle retardation region and a lower compression region, and has stronger regulating capacity but large occupied area. The high-efficiency concentration device is based on the principle of a high-density sedimentation tank, combines a reinforced flocculation process, preferably optimizes the effect of reinforcing flocculation by using an organic polymer flocculant, improves the solid content of sludge in a bottom concentration area, adopts the traditional gravity concentration tank bottom sludge solid content rate to be about 3 percent, adopts the high-efficiency concentration device bottom sludge solid content rate to be stable over 5 percent, and can directly enter a dehydration process without sludge modulation.

The high-efficiency concentration device is a high-efficiency integrated precipitation concentration tank, and consists of a reaction zone, a concentration zone and a precipitation separation zone. The process has the following five main characteristics:

(1) the special internal circulation reaction area is designed, and the medicament, water and sludge fully react;

(2) the sludge internal reflux design is adopted, and the reflux sludge is used as a condensation nucleus of flocculation reaction, so that floc is more compact;

(3) the umbrella-shaped inclined plate packing based on the shallow pool principle greatly increases the surface area of the precipitation separation area and improves the separation effect;

(4) the preferred organic polymeric flocculant is adopted to accelerate the forming of flocs and reduce the flocculation reaction time;

(5) can bear the change of the water quality and the flow of the inlet water in a larger range, and has high automation degree.

In the research of the high molecular organic flocculant on the enhanced flocculation effect: since a large amount of inorganic flocculants such as polyaluminium chloride and the like are added in the raw water treatment process of the water works, the inorganic flocculants in the discharged muddy water are in a saturated state, and the inorganic flocculants such as polyaluminium chloride or polyferric sulfate and the like are added, so that the sludge sedimentation of the discharged muddy water cannot be promoted. An organic polymeric flocculant is added, polymer bridges are formed among particles and sink together, the common organic polymeric flocculant in the sludge water treatment at present is polyacrylamide, and the organic polymeric flocculant can be classified into 3 types of cations, anions and non-ions according to the charges of the polyacrylamide.

1. The test method comprises the following steps:

the method comprises the steps of obtaining mixed sludge water in a comprehensive adjusting tank of a certain water plant, carrying out a static sedimentation test in a sedimentation column, taking bottom concentrated sludge subjected to static sedimentation for 2 hours as an object for researching the enhanced flocculation effect, uniformly shaking 1000mL of the bottom concentrated sludge into a beaker, respectively adding different types of polyacrylamide with different concentrations, mixing and reacting under certain stirring intensity and time on a synchronous six-joint stirrer, then pouring a sample into a 1000mL measuring cylinder for sedimentation for 30 minutes, and observing the numerical value of the sludge sedimentation ratio to judge the type and the adding amount of the optimal polyacrylamide.

2. The test device comprises:

the settling column adopts a 1.2.2 middle test device, a 1000ml glass measuring cylinder, a 1000ml beaker, a synchronous six-connection stirrer and the like.

3. Test results and analysis:

the experiment selects four organic polymer flocculants, namely PAM1#, PAM2#, CPAM1# and CPAM2#, and carries out a reinforced flocculation test on the concentrated sludge, and specific experimental data are shown in the following table.

Through the data analysis of the analysis, the type and the adding amount of PAM are important factors influencing the sedimentation property of the sludge water, and the larger the adding amount is, the smaller the sludge water SV30 is, the lower the turbidity of the flocculated effluent is, and the better the sedimentation property of the concentrated sludge is. When the adding amount is 30mg/L, the discharging mud SV30 after tempering by PAM1#, PAM2#, CPAM1# and CPAM2# are respectively 50%, 38%, 37% and 32%, the discharging mud SV30 is not changed greatly along with the increase of the adding amount, and the excessive PAM adding amount can cause the exceeding of PAM monomer when the flocculated water is reused. After CPAM2# is added, the sludge discharge SV30 is minimum, which shows that CPAM2# has the best effect of improving the sludge discharge sedimentation performance, the SV30 is 35% when the adding amount of CPAM2# is 20mg/L, the adding amount is obviously superior to other flocculating agents, the adding amount is continuously increased, and the SV30 change amplitude is small.

4. The feasibility of applying PAM to the sludge water flocculation treatment process is as follows:

the sludge taken in the test comes from a water supply plant which takes yellow river water as a water source, the yellow river water has poor water quality, the content of organic matters in the water is high, the content of silt is high, and the concentration and sedimentation performance of sludge water can be improved more obviously by adopting Cationic Polyacrylamide (CPAM) in the test to remove turbidity and chroma in the water. The sludge mainly contains higher-concentration colloidal particles, suspended particles and organic substances, so that the potential of the sludge water is very low, the improvement of the sedimentation performance of the sludge water is basically not feasible by changing the charge quantity in the sludge water, and the adsorption bridging and net capturing effects of high-component and high-charge-density Cationic Polyacrylamide (CPAM) are stronger, so that the sludge can be better concentrated. For a water plant which uses water with better water quality and lower organic matter content as a water source, when the organic polymeric flocculant is selected, because the water plant adds aluminum salt in the raw water treatment process flow, the Zeta potential electronegativity is obviously reduced through double electric layer compression, and the solid content of sludge can be greatly improved by adopting anionic Polyacrylamide (PAM).

In the research process of sludge backflow on the reinforced flocculation effect:

The efficient concentration device adopts a special sludge backflow process, the sludge backflow process can enhance the flocculation effect, and the backflow process can effectively improve the sedimentation speed of the sludge and greatly reduce the volume required by sludge concentration mainly through the result of synergistic effects of a flocculation core, polymer bridging, particle collision and the like.

1. Test method

Obtaining mixed sludge water in a comprehensive adjusting tank of a certain water plant, performing a static settlement test in a settling column, taking 1000mL of bottom concentrated sludge after static settlement for 2 hours, uniformly shaking the bottom concentrated sludge in a beaker, and adding 20mg/l of CPAM2# for enhanced flocculation under certain stirring strength and time; separating bottom sludge after the sludge subjected to enhanced flocculation is statically precipitated for 0.5h, discharging the bottom sludge into a beaker, uniformly stirring the bottom sludge, mixing the bottom sludge with the bottom concentrated sludge subjected to static precipitation for 2h by a settling column according to a certain proportion, adding CPAM2# with different concentrations for enhanced flocculation under certain stirring strength and time, and observing the numerical value of the sludge sedimentation ratio to judge the optimal sludge reflux ratio.

2. Testing device

The settling column adopts the test device in the experiment: a 1000ml glass measuring cylinder, a 1000ml beaker, a 1000ml separating funnel, a synchronous six-connection stirrer and the like.

3. Test results and analysis

CPAM2# organic polymer flocculant is selected in the experiment, the experiment is carried out by adding sludge after enhanced flocculation in different proportions into non-enhanced flocculation, and specific experimental data are shown in the following table.

Through the analysis of the analyzed data, for the concentrated sludge added with CPAM #2 flocculating agents with different concentrations, with the increase of the sludge reflux ratio, SV30 shows the condition of firstly decreasing and then increasing, which indicates that the reflux sludge can play the function of adsorption bridging and play the role of strengthening flocculation. With the increase of the reflux ratio, the residual turbidity is increased on the contrary, probably because when the reflux ratio is too high, the concentration of inorganic particles is increased, the excessive reflux sludge can counteract the flocculation effect of the inorganic particles on raw water, and meanwhile, the excessive CPAM enables the periphery of the sludge to adsorb more positive charges, so that Zeta is increased and stabilized again.

Therefore, the invention has the following advantages: through research on the treatment process and technical equipment, compared with the traditional sludge water treatment process, the optimized process and equipment reduce the occupied area of a water plant, reduce the engineering investment, save the energy consumption, and realize the recovery and the saving utilization of water resources.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A self-control treatment method for a sludge dewatering process of sludge discharged from a tap water plant is used for treating the sludge discharged from the tap water plant and concentrating the sludge, and is characterized by comprising the following operation steps:

2. The self-control processing method of the sludge dewatering process of the sewage water of the tap water plant as claimed in claim 1, wherein the step S1 includes the following steps of analyzing the sludge properties and performing the static sedimentation test, comprising the following steps:

SS 1: measuring the settling performance and solid content of the sludge;

SS 2: judging the properties of the sludge;

3. The self-control treatment method for the dehydration process of sludge from sewage water of tap water plant as claimed in claim 2, wherein the concrete operation steps of the sedimentation curve in the step SS1 are as follows:

。

4. the self-control treatment method of the dehydration process of sludge from water works as claimed in claim 2, wherein the concrete operation steps of the determination of the solid content in step SS1 are to determine the water content of the sludge by using the calculation formula of the water content of the sludge and the calculation formula of the solid content of the sludge,

The calculation formula of the water content of the sludge is as follows:

the calculation formula of the solid content of the sludge is as follows:

，

5. The self-control treatment method for the dehydration process of sludge from sewage water of tap water plant as claimed in claim 2, wherein the step of determining the nature of sludge in step SS2 comprises:

firstly, measuring the solid content of the sludge;

measuring the sludge dewatering performance;

measuring the properties of sludge alum floc;

6. The automatic control treatment method for the dehydration process of sludge in sewage water of tap water plant as claimed in claim 5, wherein in the step of measuring the solid content of sludge, impurities in water and sludge are adsorbed together and electrically neutralized.

7. The automatic control treatment method for the dehydration process of sludge in the sewage water of the tap water plant as claimed in claim 5, wherein the dehydration performance of the sludge in the step (II) is generally expressed by specific resistance, the smaller the specific resistance, the better the dehydration performance of the sludge, and the specific resistance is defined as the resistance of the dry solid weight of the unit filter cake on the unit filtration area;

the formula of the specific resistance is as follows:

r: specific resistance of sludge, (m/kg);

b: slope of t/V vs. V curve, (s/m)⁶）；

A: filtration area, (m)²)；

P: pressure (Pa):

c: weight of sludge cake produced per unit volume of filtrate, (kg/m)³)；

W_b: dry sludge weight, (kg);

V_f: volume of filtrate, (m)³)；

: viscosity coefficient (Pa · s).

8. The automatic control treatment method for the dehydration process of sludge from sewage water of tap water plant as claimed in claim 7, wherein the step (II) comprises:

9. The automatic control treatment method for the sludge dewatering process of the tap water plant sludge as claimed in claim 5, wherein in the step (iv), the influence of the particle size distribution on the sludge dewatering property is analyzed, and in the step (iv), a low-osmotic-pressure gradient medium is used to measure the density of alum flocs.

10. The self-control treatment method of the dehydration process of sludge from water works as claimed in claim 5, wherein in the compressibility operation step, the dehydration rate is decreased when the pressure is increased in the dehydration process, and the compressibility of the sludge is expressed by the formula:

r₁: at a pressure P₁Specific resistance of time

r₂: at a pressure P₂Specific resistance of time

S: coefficient of compression

wherein: the S value is about 0.8 to 1.5.

11. The self-control treatment method of the dehydration process of sludge from sewage water plants of the tap water plant as claimed in claim 1, wherein in step S2, cationic PAM is screened out according to step S1, and three helical blade pipeline mixing devices are used simultaneously, and the water flow is divided, cross-mixed and reverse-swirled by a pipeline mixer, so that the added chemical agent is rapidly and uniformly diffused into the whole water body, thereby achieving instantaneous mixing.

12. The self-control treatment method for the dehydration process of sludge from sewage water plant of tap water plant as claimed in claim 1, wherein in step S3, a high efficiency sedimentation concentration tank is adopted, said high efficiency sedimentation concentration tank is composed of three parts of reaction zone, concentration zone and sedimentation separation zone.

13. The self-control treatment method for the dehydration process of sludge from sewage water of tap water plant as claimed in claim 12, characterized by comprising the following steps:

14. The self-control treatment method for the dehydration process of sludge from sewage water plant of tap water plant as claimed in claim 13, wherein in step (4), the sedimentation velocity of sludge is increased and the volume required for sludge concentration is reduced by the synergistic effect of flocculation core, polymer bridging and particle collision.