Application and prospect of biotechnology in refractory wastewater and sludge treatment
First, the industrial wastewater treatment market has broad prospects
Currently, a large proportion of China's sewage discharge paper, chemicals, textiles, steel and other industries, including industrial waste water is the main source of emissions in 2015, emissions of industrial waste water accounted for 32.4% of the national total sewage discharge. At the same time, many industrial wastewater treatment facilities are not operating normally, and undocumented sewage discharge, smuggling and excessive discharge are very serious. In 2012, Dow’s “China’s Craving for Water†report pointed out that China’s industrial water reuse rate is only 25%. Therefore, large emissions, low compliance rates, and low reuse rates are serious problems faced by China's industrial wastewater discharge.
Industrial wastewater complex composition, with heavy metals, oils and toxic mainly big on the environment and human health, a single processing technology can not effectively solve, industrial wastewater treatment technology is also an urgent need to break through.
According to statistics, the scale of China's industrial wastewater treatment market in 2014-2015 is 169.7 billion yuan, but at present, the proportion of socialized operation of industrial pollution control facilities in China is only about 5%. Therefore, the industrial wastewater treatment market has broad prospects.
Second, physical and chemical pretreatment + microbial enhanced treatment process
Existing refractory industrial wastewater treatment technologies include chemical methods, physical methods, etc., with poor impact resistance, low biochemical efficiency, long time consuming, secondary pollution and residual residues, and low space for improvement. In order to solve the shortcomings of the above existing treatment technologies, the technical route of physicochemical pretreatment + microbial enhanced treatment industrial wastewater was developed. Technical indicators: in the 1T pilot and 1000T scale microbial test, the salinity range is 0-18%, COD removal The rate is >90%, the chroma removal is >99%, and the salinity is removed by 50%. At the same time, it will reduce infrastructure investment by 70% and reduce operation and maintenance by more than 40%.
The physical and chemical pretreatment + microbial enhancement treatment process includes the following core technologies:
1. Microbial diversity and strain library construction
The process establishes microbial diversity and strain library through screening and identification, strain preservation, information update, strain search, and strain application process. The types and quantities of strains currently available are as follows.
2. Functional flora construction and community analysis
This process mainly analyzes the structure and function of functional flora. Means for analysing structures include high-throughput sequencing, community gene chips, cloning, DGGE, and the like. Means for analyzing functions include metagenomic sequencing, functional gene chip, HPLC, NMR, and the like.
3. Screening of halophilic bacteria and treatment of high salinity and alkaline pollution
The halophilic screening and high-salt alkaline pollution treatment is a technology for the development of halophilic bacteria expansion for the problem of slow growth of halophilic bacteria and weak degradation ability. The technology can realize rapid biochemical reaction and rapid membrane hanging.
4. High COD industrial wastewater pretreatment technology
Industrial wastewater has high salinity, complex organic components and difficult biochemical treatment. Based on this, various pretreatment techniques have been researched and developed to solve the above problems, including electrodialysis equipment, electrodialysis packing, selective ion membrane, and active colony membrane.
5. Biological microbial agents and micro-ecological nutritional preparations
The micro-ecological nutritional preparation is a microbial agent which is fermented and cultured, and a part of the fermentation product is hydrolyzed and then mixed with different nutrients to be used as an additive for strengthening the biochemical treatment of sewage. Its composition includes sporulation functional bacteria (main components), fermentation metabolites, proteins, biological enzymes, somatotropins, etc. (promoting fractions), nitrogen, phosphorus , and other trace elements (auxiliary components). The micro-ecological nutritional preparation can enhance the cell metabolism intensity, promote proliferation, improve the oxidative decomposition ability of toxic pollutants, and improve the impact resistance and stability of the system. The processing water quality of the system is significantly improved without the need for large hardware investment.
The application of the above five technologies makes the physical and chemical pretreatment + microbial intensification treatment process compared with the traditional treatment technology, and has improved in terms of running cost, processing efficiency and management difficulty. The advantages and disadvantages are shown in the following table.
Third, technical application examples
1. Cyanide wastewater (salt 0.6%)
For Tianjin 8.12 highly toxic cyanide-containing wastewater, the active bacteria agent can be fermented for 24 hours, and put into the wastewater treatment site according to the concentration of 1010 cells/ml. The low-concentration cyanide-containing wastewater was treated for 20 hours to obtain 93% de-cyanide efficiency; the high-concentration accident wastewater was treated for 48 hours, and the CN-degradation rate was 98%.
2. Pigment wastewater (salt 1%)
The biochemical-based and physico-chemical combined process is used to enrich the functional flora in the biological aeration tank. The COD degradation rate of the wastewater is 95.22%, and the effluent color is significantly reduced after 3-4 days of treatment.
Comparison before and after wastewater treatment
3. Ultra high COD chemical wastewater (salt 5%)
Through physical and chemical parameter detection, organic matter composition analysis, microbial composition analysis and other methods, a comprehensive analysis of a super high COD chemical wastewater treatment process, revealing the current process deficiencies, and further provide basic data and guidance for process optimization. The improved treatment device uses pretreatment-biological contact oxidation technology to treat high-salt alkali chemical wastewater (salt 5%, COD 117512 mg/L), and the final COD of wastewater is ≤5000 mg/L.
Improved laboratory pilot test continuous reaction device
4. Other applications
The technology can treat dozens of high organic matter, high toxicity and heavy polluted wastewater, including salty wastewater, printing and dyeing wastewater, chemical wastewater, etc. Currently, it has provided technical services for many industrial enterprises in Tianjin, Hebei, Henan, Shandong and Zhejiang.
Fourth, the prospect of refractory industrial wastewater treatment
In the future, the treatment of refractory industrial wastewater should focus on solving the following problems, with a view to achieving better development and progress.
1. Increasing the amount of bacteria and cost control
2. High-salt wastewater and sludge suspension, flocculating properties of microbial agents
3. High salt inhibition activity and nutrient adjustment
4. Sludge backflow and sludge performance maintenance and preservation
5. Upstream and downstream process integration / activated sludge activity supplement and pressure buffer
6. Development and application of continuous flow adding agent production equipment
7. Recycling of materials in industrial wastewater
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