CN104743760A - Method for synchronously implementing sludge strengthened dewatering and increasing bio-adsorbent yield - Google Patents

Abstract

The invention relates to a method for synchronously realizing enhanced dehydration of sludge and increasing production of biosorbent. First obtain the remaining sludge from the urban sewage treatment plant that adopts the biological treatment process, and measure the surfactant according to the mass ratio: sludge dry weight = 0.01-0.3:1; Finally, the sludge is subjected to mechanical pressure filtration, and the mud cake after pressure filtration is dewatered sludge, and the filtrate is a liquid biosorbent, and the filtrate is stored in a refrigerator at 0-5°C for future use. The invention not only strengthens the sludge dewatering effect, but also increases the output of the biosorbent, and simultaneously realizes the reduction and resource utilization of excess sludge. Compared with the aerobic fermentation process of remaining sludge under the same conditions without adding surfactant, the yield of biosorbent is increased by 1.8-2.7 times, and the moisture content of mud cake is reduced by 7.7%-15.8%.

Description

A method for synchronously realizing enhanced dehydration of sludge and increasing production of biosorbent

technical field

The invention relates to a method for synchronously realizing enhanced dehydration of sludge and increasing the yield of biosorbent, and belongs to the technical field of environmental protection.

Background technique

With the acceleration of urbanization in my country and the continuous increase of urban population in recent years, the amount of urban sewage treatment in my country is increasing, which leads to the continuous increase in the output of by-products and residual sludge produced in the process of sewage treatment. The "National Environmental Protection "Twelfth Five-Year" Plan" pointed out: In 2015, our sewage treatment capacity was 47.5 billion tons. If every 10,000 tons of sewage is processed, 7.5 tons of residual activated sludge with a moisture content of 80% (dehydrated sludge will be produced) Cake), my country will produce 35.125 million tons of surplus activated sludge in 2015. Residual sludge contains a large amount of water, complex organic substances, various heavy metal toxic substances, pathogenic bacteria, virus microorganisms and other harmful substances. If it is piled up or landfilled without any treatment, it will cause serious pollution to the environment.

However, excess sludge is not only a waste material and environmental pollutant produced by sewage treatment plants, but also a good organic resource. It is an aggregate composed of bacterial micelles formed by various microorganisms and their adsorbed organic and inorganic substances. The content of organic substances is about 60%, and the biodegradable organic components are more than 40%. These biodegradable organic substances are mainly It is an organic polymer substance such as protein, polysaccharide, nucleic acid, etc. The functional groups contained in these organic polymers can provide numerous adsorption sites for the adsorption process, so they can be used as biosorbents for the treatment of wastewater containing heavy metals. The biosorbent has the advantages of simple preparation, energy saving and low cost, high removal rate, and easy separation and recovery of heavy metals. Obviously, if the excess sludge can be used to prepare biosorbents, it will not only reduce its pollution to the environment, but also produce biosorbents with high-efficiency heavy metal adsorption performance, thus realizing the reduction and stabilization of excess sludge , Recycling and reducing environmental pollution. Chinese invention patent 201310234516.8 discloses the process of using excess sludge to prepare heavy metal biosorbents, specifically performing aerobic fermentation first, then ultrasonic treatment, and finally centrifugal separation.

Contents of the invention

The purpose of the present invention is to provide a method for synchronously realizing enhanced sludge dewatering and increasing biosorbent production. The method of the invention can not only strengthen the sludge dehydration effect, but also increase the output of the heavy metal biosorbent, and simultaneously realize the reduction and resource utilization of excess sludge.

In order to achieve the above object, the research of the present invention finds that: the aerobic fermentation of excess sludge is under aerobic conditions, utilizing the activity of microorganisms in excess sludge to further utilize the small molecular organic matter adsorbed on the surface of bacterial cells and transform them into bacterial cells and the secretions of bacteria micelles, and the polysaccharides, proteins and nucleic acids contained in these bacteria and secretions have a good adsorption effect on heavy metal ions. After aerobic fermentation, the concentration of organic matter in the sludge supernatant was greatly reduced under the adsorption and metabolism of living bacteria and bacteria micelles. At the same time, extracellular polymers have an important impact on the dewatering performance of activated sludge. One of the reasons why sludge is difficult to dewater is due to the existence of extracellular polymers, which surround bacteria like capsules, and their presence makes more The water is combined in the activated sludge flocs, and this part of water is difficult to remove by mechanical dehydration, so the higher the content of extracellular polymers in the activated sludge, the worse the dehydration performance.

Surfactants have "amphiphilic" properties, hydrophilic and lipophilic properties, and also have a "solubilizing" effect. Therefore, surfactants can be used to promote the release of extracellular polymers in excess sludge, making them wrapped in cells The bound water in the outer polymer is transformed into free water, thereby achieving enhanced sludge dewatering and increased biosorbent production. So far, no research has been reported on the simultaneous use of surfactants to enhance sludge dewatering and biosorbent production. For this reason, the present invention first obtains excess sludge from urban sewage treatment plants adopting biological treatment process, and measures surfactant by mass ratio: sludge dry weight=0.01～0.3:1; then they are mixed evenly and carried out aerobic fermentation Cultivation, and then perform mechanical pressure filtration on the fermented sludge, the mud cake after the pressure filtration is the dewatered sludge, and the filtrate is the liquid biosorbent, and the filtrate is stored in the refrigerator at 0-5°C for later use;

Above-mentioned surfactant is anionic surfactant, or cationic surfactant, or nonionic surfactant, or amphoteric surfactant, or biosurfactant;

The above-mentioned uniform mixing means that the surfactant and the sludge are evenly mixed by mechanical stirring or aeration stirring;

The above-mentioned aerobic fermentation culture is to put the remaining sludge with a pH of 5-9 and a concentration of 3-15g/L into the fermenter for fermentation, and achieve a dissolved oxygen concentration of 0.5-6.5mg/L in the fermenter through aeration. The fermentation temperature is 25-55°C, and the fermentation time is 2-24 hours;

The above-mentioned mechanical press filter is to dehydrate the fermented sludge by using plate and frame dehydration, or belt dehydration, or centrifugal dehydration, or screw stack dehydration.

The present invention has the following advantages and effects:

(1) Using the surplus sludge of urban sewage treatment plants, the synergistic effect of surfactant and aerobic fermentation has greatly improved the production of biosorbents prepared from sludge, not only realizing sludge reduction, stabilization, and resource utilization It is a sustainable development circular economy model for urban sewage treatment plants.

(2) The heavy metal biosorbent produced can be used for wastewater treatment containing heavy metal ions, and heavy metals are recovered while sewage treatment is realized. Due to the low cost of preparing heavy metal biosorbents from surplus sludge, the heavy metal biosorbents have a high adsorption capacity for heavy metal ions. Therefore, the treatment cost of wastewater containing heavy metal ions can be reduced, and the dual benefits of pollution control and resource recovery can be realized.

(3) While the surfactant promotes the release of macromolecules such as extracellular polymers, the bound water wrapped in the extracellular polymers becomes free water, and the preparation of biosorbents is realized through the mud-water separation method of mechanical dehydration. At the same time, it also strengthens the dehydration effect of sludge, which has important guiding significance for improving and optimizing the existing sludge treatment system and reducing investment costs.

Detailed ways

Example 1

This embodiment adopts traditional process, namely carries out aerobic fermentation under the same condition without adding surfactant. The specific process is: in a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.7%, sludge concentration is 8.02g/L, pH=7.02) as the preparation of biological The raw material of the adsorbent is to maintain the dissolved oxygen concentration in the reactor at 2-3 mg/L at room temperature. The aerobic fermentation time of the remaining sludge in the reactor is 4-8 hours, and the fermented sludge is suction-filtered for 30 minutes under a constant pressure of 0.05MPa, and the output of the biosorbent contained in the filtrate is 13.28-22.06mg/gVSS (unit weight The yield of biosorbent in the volatile suspended solids), the water content of mud cake is 78.87%～82.21%, the fermented sludge is centrifuged at 12000 rpm, 4 ℃ for 10 minutes, and the supernatant obtained by centrifugation is detected and analyzed The yield of the biosorbent contained in the liquid is 12.82-20.23mg/gVSS (the yield of the biosorbent in the volatile suspended solid per unit weight). The water content of the bottom mud cake obtained by centrifugation is 80.38-85.42%.

Example 2

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.7%, sludge concentration is 8.02g/L, pH=7.02) as raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3mg/L, add anionic surfactant sodium dodecylbenzenesulfonate. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 8 hours, and the fermented sludge is suction filtered at a constant pressure of 0.05MPa for 30 minutes, and the filtrate The output of contained biosorbent is 82.28mg/gVSS (the output of biosorbent in the volatile suspended solid of unit weight), and the water content rate of mud cake is 69.56%, and does not add anionic surfactant dodecylbenzene sulfonate Compared with sodium bicarbonate, the yield of biosorbent increased by more than 2.7 times, and the water content of mud cake decreased by more than 11.8%.

Example 3

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.7%, sludge concentration is 8.02g/L, pH=7.02) as raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3 mg/L, and add a cationic surfactant, hexadecyldimethylammonium bromide. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.05:1, and the aerobic fermentation time of the remaining sludge in the reactor is 4 hours. The output of contained biosorbent is 70.82mg/gVSS (the output of biosorbent in the volatile suspended solid of unit weight), the moisture content of mud cake is 66.38%, and does not add cationic surfactant cetyl dimethyl Compared with ammonium bromide, the yield of biosorbent increased by more than 2.2 times, and the water content of mud cake decreased by more than 15.8%.

Example 4

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.7%, sludge concentration is 8.02g/L, pH=7.02) as raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3 mg/L, and add non-ionic surfactant Tween-80. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 4 hours, and the fermented sludge is suction filtered at a constant pressure of 0.05MPa for 30 minutes, and the filtrate The output of contained biosorbent is 64.62mg/gVSS (the yield of biosorbent in the volatile suspended solids of unit weight), and the moisture content of mud cake is 72.52%, and does not add non-ionic surfactant Tween-80 phase Compared with that, the output of biosorbent increased by more than 1.9 times, and the water content of mud cake decreased by more than 8.1%.

Example 5

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 96.9%, sludge concentration is 8.10g/L, pH=6.98) as a raw material for preparing biosorbent , at room temperature, maintain the concentration of dissolved oxygen in the reactor at 2-3mg/L, and add the zwitterionic surfactant 2-alkyl-N-hydroxyethyl-N-hydroxypropylsulfoimidazoline. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 4 hours, and the fermented sludge is suction filtered at a constant pressure of 0.05MPa for 30 minutes, and the filtrate The output of contained biosorbent is 61.72mg/gVSS (the yield of biosorbent in the volatile suspended solid of unit weight), the moisture content of mud cake is 71.41%, and does not add zwitterionic surfactant 2-alkyl Compared with -N-hydroxyethyl-N-hydroxypropyl sulfoimidazoline, the yield of the biosorbent is increased by more than 1.8 times, and the water content of the mud cake is reduced by more than 9.5%.

Example 6

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 96.9%, sludge concentration is 8.10g/L, pH=6.98) as a raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3 mg/L, and add bio-surfactant rhamnolipid. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 8 hours, and the fermented sludge is suction filtered at a constant pressure of 0.05MPa for 30 minutes, and the filtrate The output of contained biosorbent is 64.73mg/gVSS (the output of biosorbent in the volatile suspended solid of unit weight), and the water content rate of mud cake is 72.82%, and does not add biotype surfactant rhamnolipid phase Compared with that, the output of biosorbent increased by more than 1.9 times, and the water content of mud cake decreased by more than 7.7%.

Example 7

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.1%, sludge concentration is 8.07g/L, pH=6.98) as a raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3 mg/L, and add a cationic surfactant, hexadecyldimethylammonium bromide. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.05:1, the aerobic fermentation time of the remaining sludge in the reactor is 4 hours, and the fermented sludge is centrifuged at 12,000 rpm and 4°C for 10 Minutes, the output of biosorbent contained in the supernatant is 63.67mg/gVSS (the yield of biosorbent in the volatile suspended solids of unit weight), the water content of bottom mud cake is 70.38%, and does not add cationic surfactant Compared with cetyl dimethyl ammonium bromide, the yield of biosorbent increased by more than 2.1 times, and the water content of mud cake decreased by more than 12.4%.

Example 8

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.1%, sludge concentration is 8.07g/L, pH=6.98) as a raw material for preparing biosorbent , at room temperature, maintain the dissolved oxygen concentration in the reactor at 2-3mg/L, add anionic surfactant sodium dodecylbenzenesulfonate. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 8 hours, and the fermented sludge is centrifuged at 12,000 rpm and 4°C for 10 Minutes, the output of biosorbent contained in the supernatant is 74.89mg/gVSS (the yield of biosorbent in the volatile suspended solids of unit weight), the moisture content of bottom mud cake is 73.38%, and does not add anionic surfactant Compared with sodium dodecylbenzene sulfonate, the yield of biosorbent increased by more than 2.7 times, and the water content of mud cake decreased by more than 8.7%.

Example 9

In a cylindrical reactor with a working volume of 5 liters made of plexiglass, add excess sludge (its moisture content is 97.3%, sludge concentration is 8.04g/L, pH=7.08) as raw material for preparing biosorbent , at room temperature, maintain the concentration of dissolved oxygen in the reactor at 2-3mg/L, and add the zwitterionic surfactant 2-alkyl-N-hydroxyethyl-N-hydroxypropylsulfoimidazoline. The microorganisms in the sludge use the organic matter in the sludge supernatant to transform into their own metabolites—biosorbents. Through the solubilization of surfactants, the biosorbents surrounded on the surface of microbial cell membranes are released into the solution. The bound water wrapped in the extracellular polymer becomes free water, and the preparation of biosorbent and the enhanced dehydration of sludge are realized at the same time. Among them, the ratio of the amount of surfactant to the dry weight of the sludge is 0.1:1, the aerobic fermentation time of the remaining sludge in the reactor is 4 hours, and the fermented sludge is centrifuged at 12,000 rpm and 4°C for 10 Minutes, the output of biosorbent contained in the supernatant is 60.21mg/gVSS (the yield of biosorbent in the volatile suspended solids of unit weight), the water content of bottom mud cake is 71.92%, and does not add amphoteric ion Compared with the surfactant 2-alkyl-N-hydroxyethyl-N-hydroxypropyl sulfoimidazoline, the yield of the biosorbent is increased by more than 2.0 times, and the water content of the mud cake is reduced by more than 10.5%.

Claims (1)

1. synchronously realize a method for mud strengthen dewatering and raising biological adsorption agent output, it is characterized in that:

First from adopting the urban wastewater treatment firm of biological treatment to obtain excess sludge, measure tensio-active agent in mass ratio: mud dry weight=0.01-0.3:1; They mixed, then carry out aerobic fermentation cultivation, finally carry out mechanism filter-pressing to mud after fermentation, after press filtration, mud cake is dewatered sludge, and filtrate is liquid biological sorbent material, filtrate is placed on preservation at 0-5 DEG C in refrigerator, for subsequent use;

Above-mentioned tensio-active agent is anion surfactant, or cats product, or nonionogenic tenside, or amphoterics, or bio-surfactant;

Above-mentioned mixing adopts mechanical stirring or aeration agitation mode that tensio-active agent is mixed with mud;

It is be 5-9 by pH that above-mentioned aerobic fermentation is cultivated, and concentration is that the excess sludge of 3-15g/L is put into fermentor tank and fermented, and make dissolved oxygen concentration in fermentor tank be 0.5-6.5mg/L by aeration, leavening temperature is 25-55 DEG C, and fermentation time is 2-24h;

Above-mentioned mechanism filter-pressing is that mud after fermentation is adopted sheet frame dehydration, or belt type dehydration, or centrifuge dehydration, or the dehydration of folded spiral shell.