CN105923747B - Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and method - Google Patents

Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and method Download PDF

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Publication number
CN105923747B
CN105923747B CN201610243569.XA CN201610243569A CN105923747B CN 105923747 B CN105923747 B CN 105923747B CN 201610243569 A CN201610243569 A CN 201610243569A CN 105923747 B CN105923747 B CN 105923747B
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promoting
growth
industrial wastewater
biology
weight
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CN201610243569.XA
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CN105923747A (en
Inventor
薛罡
张文启
高品
李响
徐晨岚
韩闯
刘振鸿
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Donghua University
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Donghua University
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/10Packings; Fillings; Grids
    • C02F3/105Characterized by the chemical composition
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/30Aerobic and anaerobic processes
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/34Biological treatment of water, waste water, or sewage characterised by the microorganisms used
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/30Nature of the water, waste water, sewage or sludge to be treated from the textile industry
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/343Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the pharmaceutical industry, e.g. containing antibiotics
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2203/00Apparatus and plants for the biological treatment of water, waste water or sewage
    • C02F2203/006Apparatus and plants for the biological treatment of water, waste water or sewage details of construction, e.g. specially adapted seals, modules, connections
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00Use of specific compounds during water treatment
    • C02F2305/06Nutrients for stimulating the growth of microorganisms
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

Abstract

The present invention provides a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and methods.The Industrial Wastewater Treatment biology in situ growth-promoting intensifying device, it is characterized in that, including aerobic tank, biological growth-promoting Controlled-release filler is loaded in the aerobic tank, the biological growth-promoting Controlled-release filler includes ferromanganese grain, iron-copper grain, haydite, active carbon, zeolite, limonite, combination growth-promoting agent;Wherein, the combination growth-promoting agent includes sodium acetate, starch, glucose, vitamin B and vitamin E.The present invention passes through biology in situ growth-promoting intensifying method, the activity and quantity of dominant bacteria in industrial wastewater Aerobic biological process can be effectively improved, to improve biological treatment structures to the removal efficiency of hardly degraded organic substance in waste water, and then reaches discharge of wastewater and propose target requirement.

Description

Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and method
Technical field
The invention belongs to industrial waste water treatment, in particular to a kind of Industrial Wastewater Treatment biology in situ growth-promoting is strong Change device and method.
Background technique
Currently, industrial wastewater discharge standard generally improves.Previous Industrial Wastewater Treatment continues to use anaerobism (or hydrolysis acid mostly Change), the biological treatments group technology such as aerobic is difficult to reach new after discharge standard generally improves using the conventional combination technique Discharge standard.And industrial wastewater is limited to the reasons such as the toxicity of water quality, refractory organics, it is natural in Aerobic biological process structures It is aerated under growth conditions, there is the dominant bacteria activity of single-minded degradation and quantity to be difficult to greatly organic matter degradation in biological treatment Amplitude improves, and organic matter degradation efficiency is also difficult to further increase.And the mark transformation that mentions of industrial wastewater is concentrated mainly on by force at present Change pretreatment and two links of advanced treating, but the two approach are both needed to newly-built treatment facility, newly-increased investment, operating cost also compared with It is high.Propose mark investment for trnasforming urban land and the high problem of operating cost for industrial wastewater, as can by biological treatment structures in waste water Hardly degraded organic substance has the dominant bacteria activity of single-minded degradation and quantity to improve, then can not augment pretreatment and depth On the basis of managing facility, dominant bacteria is to organic matter degradation efficiency in waste water in raising biological treatment, to make water quality after processing It improves.
Summary of the invention
The object of the present invention is to provide a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and methods, useless to improve Water treatment efficiency.
In order to achieve the above object, the present invention provides a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying device, It is characterized in that, including aerobic tank, biological growth-promoting Controlled-release filler, the biological growth-promoting Controlled-release filler is loaded in the aerobic tank Including ferromanganese grain, iron-copper grain, haydite, active carbon, zeolite, limonite, combination growth-promoting agent;Wherein, the combination Growth-promoting agent includes sodium acetate, starch, glucose, vitamin B and vitamin E.
Preferably, the biological growth-promoting Controlled-release filler includes 30 parts by weight of ferromanganese grain, 30 weight of iron-copper grain Part, 10 parts by weight of haydite, 10 parts by weight of active carbon, 5 parts by weight of zeolite, 5 parts by weight of limonite and combination 5 parts by weight of growth-promoting agent.
Preferably, the combination growth-promoting agent includes sodium acetate 30% (weight percent), 30% (weight percent of starch Than), 5.0% (weight percent of glucose 30% (weight percent), vitamin B 5.0% (weight percent) and vitamin E Than), preparation method are as follows: after mixing above-mentioned substance, add water and stir and be slurried, then pinch into the ball that partial size is 10~15mm Shape obtains combination growth-promoting agent after desiccation.Preferably, the biological growth-promoting Controlled-release filler the preparation method comprises the following steps: by above-mentioned biology Each ingredient of growth-promoting Controlled-release filler presses set weight ratio, and every 20kg is packaged as one with the nylon net bag that eyelet aperture is 1.0~2.0mm Bag.Preferably, the biological growth-promoting Controlled-release filler outer packaging nylon net bag, will be by more bags of biological growth-promoting sustained releases with nylon rope Filler is worn bunchiness and is hung in aerobic tank.
The present invention also provides a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying methods, which is characterized in that in use The Industrial Wastewater Treatment biology in situ growth-promoting intensifying device stated, comprising: industrial wastewater is handled using aerobic tank, is processed Cheng Zhong, the biological growth-promoting Controlled-release filler in aerobic tank have growth-promoting work to the indigenous strain of the organic matter in the industrial wastewater that can degrade With.
Preferably, the industrial wastewater is printing and dyeing, chemical industry or waste water of pharmaceutical industry.
The principle of the present invention is: in industrial wastewater biological treatment, the active sludge intermixture in aerobic unit being passed through Activation, the repair of the microelement, high-quality carbon source of biological growth-promoting Controlled-release filler release, are improved in Aerobic biological process to difficulty Degradation of organic substances has the quantity and enzymatic activity of the indigenous dominant bacteria of single-minded effect, to improve difficult to degrade organic in industrial wastewater The removal effect of object.Method of the invention proposes mark transformation for industrial wastewater, is not required to newly-built treatment facility, with low investment and be easy to Operation.
By means of the present invention, the significant effect that industrial wastewater Aerobic biological process can be removed to organic matter improves, and It saves wastewater treatment and proposes mark transformation supplement pretreatment and the investment and operating cost of advanced treating.
Beneficial effects of the present invention:
(1) present invention can be effectively improved excellent in industrial wastewater Aerobic biological process by biology in situ growth-promoting intensifying method The activity and quantity of gesture strain, to improve biological treatment structures to the removal efficiency of hardly degraded organic substance in waste water, in turn Reach discharge of wastewater and proposes target requirement;
(2) unlike mentioning mark renovation technique from supplement pretreatment and advanced treatment facility etc., biology in situ of the invention Growth-promoting intensifying method has greater advantage in terms of investment and operating cost without increasing waste water disposal facility;
(3) operation of the present invention is simple, investment and operating cost are low, is easy to engineering construction.
Detailed description of the invention
Fig. 1 is the process flow of Industrial Wastewater Treatment biology in situ growth-promoting reinforcement technique in the present invention.
Specific embodiment
Present invention will be further explained below with reference to specific examples.It should be understood that these embodiments are merely to illustrate the present invention Rather than it limits the scope of the invention.In addition, it should also be understood that, after reading the content taught by the present invention, those skilled in the art Member can make various changes or modifications the present invention, and such equivalent forms equally fall within the application the appended claims and limited Range.
Comparative example 1
Certain dyeing waste water centralized treatment plant, treatment scale 30000m3/ d, discharge is useless after collecting each printing and dyeing enterprise pretreatment Water, waste water treatment plant influent COD=400~500mg/L, successively through Anaerobic Treatment (reaction time 6h), anoxic treatment (reaction Time is 6h), after Aerobic Process for Treatment (reaction time 18h), utilize secondary settling tank (surface loading 1.5m3/m2H, sedimentation time It is discharged, is transported outward after a part of concentrated, dehydration of the sludge in secondary settling tank, another portion after handling for 2.0h) industrial wastewater Divide and flows back into Anaerobic Treatment, anoxic treatment and aerobic treatment process.
After processing, it is discharged COD=150~200mg/L, is unable to reach " urban wastewater treatment firm pollutant emission standard " (GB18918-2012) level-one B discharge standard (COD≤60mg/L) in.
Embodiment 1
A kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying device, including aerobic tank load life in the aerobic tank Object growth-promoting Controlled-release filler, the biological growth-promoting Controlled-release filler is by ferromanganese grain (3.0~4.0mm of partial size, iron: manganese mass ratio =10: 1~20: 1) 30 parts by weight, iron-copper grain (3.0~4.0mm of partial size, iron: copper mass ratio=10: 1~20: 1) 30 weight Measure part, haydite (commercially available, 3.0~4.0mm of partial size) 10 parts by weight, active carbon (commercially available, 4.0~5.0mm of partial size) 10 parts by weight, boiling Stone (commercially available, 4.0~5.0mm of partial size) 5 parts by weight, limonite (commercially available, 4.0~5.0mm of partial size) 5 parts by weight and combination growth-promoting agent 5 parts by weight composition.The combination growth-promoting agent is by sodium acetate 30wt% parts by weight, starch 30wt% parts by weight, glucose 30wt% parts by weight, vitamin B 5.0wt% parts by weight and vitamin E 5.0wt% parts by weight composition, preparation method are as follows: will It after above-mentioned substance mixes, adds water and stirs and is slurried, then pinch into the pellet that partial size is 10~15mm, combination is obtained after desiccation and is promoted Raw agent.The biological growth-promoting Controlled-release filler the preparation method comprises the following steps: by above-mentioned biological each ingredient of growth-promoting Controlled-release filler by set heavy Ratio is measured, every 20kg is packaged as one bag with the nylon net bag that eyelet aperture is 1.0~2.0mm.The biological growth-promoting Controlled-release filler Outer packaging nylon net bag will wear bunchiness by more bags of biological growth-promoting Controlled-release fillers with nylon rope and hang in aerobic tank.It is described Industrial Wastewater Treatment biology in situ growth-promoting intensifying device can pass through the aerobic of the dyeing waste water centralized treatment plant in comparative example 1 The biological growth-promoting Controlled-release filler is loaded in pond to obtain.The loadings of biological growth-promoting Controlled-release filler are in the aerobic tank 40kg/(m3Aerobic tank pool capacity).
As shown in Figure 1, a kind of Industrial Wastewater Treatment heterotopic biological growth-promoting intensifying method, using above-mentioned Industrial Wastewater Treatment Heterotopic biological growth-promoting intensifying device, specific steps are as follows: the COD=that will be discharged after the pretreatment of printing and dyeing enterprise described in comparative example 1 The waste water of 400~500mg/L, successively through Anaerobic Treatment (reaction time 6h), anoxic treatment (reaction time 6h), aerobic After carrying out Aerobic Process for Treatment (reaction time 18h) in pond, secondary settling tank (surface loading 1.5m is utilized3/m2H, sedimentation time be Solid-liquid separation treatment 2.0h) is carried out to industrial wastewater, precipitating supernatant is to be discharged after handling, the precipitating sludge in secondary settling tank one It is transported outward after lease making concentration, dehydration, another part flows back into Anaerobic Treatment, anoxic treatment and aerobic treatment process.It is aerobic utilizing Pond to industrial wastewater in the process of processing, it is biological growth-promoting Controlled-release filler in aerobic tank release various trace elements, high-quality Carbon source has growth-promoting functions, the activity and quantity of indigenous dominant bacteria to the indigenous strain of the organic matter in the industrial wastewater that can degrade It significantly improves, water quality significantly improves after processing and COD stably reaches 60mg/L or less.

Claims (6)

1. a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying device, which is characterized in that including aerobic tank, the aerobic tank The biological growth-promoting Controlled-release filler of middle filling, the biological growth-promoting Controlled-release filler include ferromanganese grain, iron-copper grain, haydite, Active carbon, zeolite, limonite, combination growth-promoting agent;Wherein, the combination growth-promoting agent includes sodium acetate, starch, glucose, dimension Raw element B and vitamin E;The combination growth-promoting agent includes sodium acetate 30%(weight percent), starch 30%(weight percent), Glucose 30%(weight percent), vitamin B 5.0%(weight percent) and vitamin E 5.0%(weight percent), system Preparation Method are as follows: after mixing above-mentioned substance, add water and stir and be slurried, the pellet that partial size is 10 ~ 15mm is then pinched into, after desiccation Obtain combination growth-promoting agent.
2. Industrial Wastewater Treatment biology in situ growth-promoting intensifying device as described in claim 1, which is characterized in that the biology Growth-promoting Controlled-release filler includes 30 parts by weight of ferromanganese grain, 30 parts by weight of iron-copper grain, 10 parts by weight of haydite, 10 weight of active carbon Measure part, 5 parts by weight of zeolite, 5 parts by weight of limonite and combination 5 parts by weight of growth-promoting agent.
3. Industrial Wastewater Treatment biology in situ growth-promoting intensifying device as described in claim 1, which is characterized in that the biology Growth-promoting Controlled-release filler the preparation method comprises the following steps: above-mentioned biological each ingredient of growth-promoting Controlled-release filler is pressed set weight ratio, every hole 20kg Eyelet diameter is that the nylon net bag of 1.0 ~ 2.0mm is packaged as one bag.
4. Industrial Wastewater Treatment biology in situ growth-promoting intensifying device as described in claim 1, which is characterized in that the biology Growth-promoting Controlled-release filler outer packaging nylon net bag will wear bunchiness by more bags of biological growth-promoting Controlled-release fillers with nylon rope and hang on In oxygen pond.
5. a kind of Industrial Wastewater Treatment biology in situ growth-promoting intensifying method, which is characterized in that using any one of claim 1-4 The Industrial Wastewater Treatment biology in situ growth-promoting intensifying device, comprising: industrial wastewater is handled using aerobic tank, is handled In the process, the biological growth-promoting Controlled-release filler in aerobic tank has growth-promoting to the indigenous strain of the organic matter in the industrial wastewater that can degrade Effect.
6. Industrial Wastewater Treatment biology in situ growth-promoting intensifying method as claimed in claim 5, which is characterized in that the industry Waste water is printing and dyeing, chemical industry or waste water of pharmaceutical industry.
CN201610243569.XA 2016-04-19 2016-04-19 Industrial Wastewater Treatment biology in situ growth-promoting intensifying device and method Expired - Fee Related CN105923747B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5846425A (en) * 1994-07-22 1998-12-08 Whiteman; George R. Methods for treatment of waste streams
CN1526660A (en) * 2003-09-25 2004-09-08 同济大学 Functional suspended stuffing
CN101892157A (en) * 2010-08-18 2010-11-24 孙廷震 Composite microbial inoculum for preparing biological bacterial fertilizer and preparation method thereof
CN102250768A (en) * 2011-06-01 2011-11-23 康源绿洲微生物技术(北京)有限公司 Method for preparing enzyme and bacterium composite agent for treating sewage and sludge

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5846425A (en) * 1994-07-22 1998-12-08 Whiteman; George R. Methods for treatment of waste streams
CN1526660A (en) * 2003-09-25 2004-09-08 同济大学 Functional suspended stuffing
CN101892157A (en) * 2010-08-18 2010-11-24 孙廷震 Composite microbial inoculum for preparing biological bacterial fertilizer and preparation method thereof
CN102250768A (en) * 2011-06-01 2011-11-23 康源绿洲微生物技术(北京)有限公司 Method for preparing enzyme and bacterium composite agent for treating sewage and sludge

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