Novel technology for treating low-carbon-nitrogen-ratio domestic sewage

Abstract

The invention relates to environmental protection technologies, in particular to a novel technology for low-carbon-nitrogen-ratio domestic sewage. When an existing technology is used for treating low-carbon-nitrogen-ratio domestic sewage, competition of a carbon source is generated due to anaerobic phosphorus release and denitrification nitrogen removal; the metabolism period of nitrifying bacteria is long, and the metabolism period of heterotrophic bacteria and polyphosphate accumulating bacteria is short; oxygen competition is generated due to nitrifying bacteria and the heterotrophic bacteria, and the nitrifying bacteria can not be a dominant population unless organic matter is degraded thoroughly; in addition, the number of structures is large, energy consumption is high, the cost is high, and operation is troublesome. In order to solve the existing problems, the novel technology includes the steps that the domestic sewage enters an anaerobic tank, mud and water mixed liquid in the anaerobic tank enters a settling tank, supernate of the settling tank flows automatically to an aerobic biofilm nitrifying tank, meanwhile, aeration is performed to provide dissolved oxygen (DO), settled sewage sludge overreaches to an oxygen deficit tank, mud and water mixed liquid of the oxygen deficit tank enters the settling tank, the supernate of the settling tank is discharged, the settled sewage sludge flows back to the anaerobic tank, and sewage discharging meets first-class A discharge standards of national discharge standards of pollutants in town sewage factories (GB18918-2002). The novel technology has the advantages that the sewage treatment effect is good; it is unnecessary to additionally arrange a carbon source; energy consumption is low, and the treatment cost for the sewage is low; the building cost of the technology is low, and the operation method is simple; the environment is protected, and water environment quality is easily improved.

Description

technical field [0001] The invention relates to environmental protection technology, in particular to a new process for treating domestic sewage with a low carbon-to-nitrogen ratio. Background technique [0002] With the rapid development of the economy, the eutrophication of water bodies is becoming more and more serious, such as Chaohu Lake, Taihu Lake and Dianchi Lake. Nitrogen and phosphorus are two important factors that cause water eutrophication, and many countries have strict restrictions on their discharge concentration. The Ministry of Environmental Protection of my country requires that when the effluent of urban sewage treatment plants is discharged into key river basins, lakes, reservoirs and other closed and semi-enclosed waters, the first-level A standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002) must be strictly implemented . [0003] In order to meet the standard discharge of nitrogen and phosphorus in domestic sewa...

AI Technical Summary

Problems solved by technology

However, for a long time, the C / N of urban domestic sewage in my country has been relatively low. More than 65% of sewage treatment plants have insufficient carbon sources. Nearly 43% of sewage treatment plants have influent C / N less than 3, and the carbon in sewage Sources can no longer meet the needs of microbial nitrogen and phosphorus removal

Therefore, using A 2 When the O process is used to treat domestic sewage, there is usually this outstanding problem: the competition between denitrification and denitrification and phosphorus removal microorganisms for carbon sources. Since the carbon source of urban sewage is generally low, it is difficult to meet the needs of nitrogen and phosphorus removal. Therefore, after treatment The sewage nitrogen and phosphorus are difficult to meet the discharge standards

In addition, this work also has the following disadvantages: the coexistence of different sludge age (Solids Retention Time, SRT) microorganisms has an adverse effect on the removal of nitrogen and phosphorus, the generation time of phosphorus accumulating bacteria is short, and they can grow normally under the condition of short SRT. And can obtain higher phosphorus removal efficiency, while nitrifying bacteria are autotrophic obligate aerobic bacteria, its growth rate is slow, and the generation time is longer. Under the condition of longer SRT, better nitrogen removal efficiency can be obtained. Therefore, the difference in SRT between nitrifying bacteria and phosphorus accumulating bacteria also leads to low efficiency of nitrogen and phosphorus removal in domestic sewage

Although this process has achieved good results in the treatment of low C / N ratio domestic sewage, the process requires many structures (1 anaerobic tank, 1 aerobic nitrification tank, 1 anoxic tank, and a post-aeration tank 1, 3 sedimentation tanks), the operation consumes a lot of energy, and it is difficult to really apply it to the actual sewage treatment

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