The activated sludge method was used to treat the alkali residue wastewater after pretreatment in a refinery. The activated sludge was domestically acclimated with the target wastewater as the carbon source, and then the domesticated alkali sludge was treated with domesticated activated sludge to reduce its COD (chemical oxygen demand) value. The experimental results show that the biochemical treatment of activated sludge has a significant reduction effect on the COD value of the alkali residue wastewater. Under the conditions of hydraulic retention time of 24 h, the average removal rate of COD is up to 76% and the volume load is about 0.7 kg COD / (m3 • d). After 10 days of operation, the total COD removal rate can reach about 74% Water quality reached the national emission standards (GB 8978-1996).
Refining caustic soda wastewater is the waste caustic soda generated during the alkaline scrubbing of petroleum products during the oil refining process. The main components are Na2S, mercaptans, thioethers, thiophenes, phenols, quinones and naphthenic acids, which are difficult to handle in high concentration organic One of the waste water. At present, researchers use a variety of treatment technologies based on the characteristics of industrial wastewater, including high-temperature wet oxidation and mild wet air oxidation. The United States Zimpro company first developed a wet air oxidation of industrial applications, and its application in the treatment of harmful petrochemical waste and waste. The process of organic and sulfide treatment efficiency, but the reactor requirements (high temperature, high pressure).
This kind of wet oxidation technology has a good effect on wastewater treatment, but requires large equipment investment and high energy consumption, which can not completely mineralize nitrogenous compounds and PCBs, thus limiting its wide application. Wright Chemical Company for many years and South Korea SK Group Institute of Biological Experimentation, SK will be highly efficient biological treatment technology used in the treatment of high-concentration caustic wastewater, the creation of the Wright bio-technology. This process has high adaptability to changes of pollutant concentration, poison concentration and salinity in wastewater.
However, the phenomenon of temperature increase during the operation of the process is obvious, which will seriously reduce the oxygen-dissolving capacity of the muddy water mixture in the reactor and reduce the microbial activity. Han Jianhua on the wet oxidation of sulfur-containing refinery caustic sludge made in-depth study, put forward a 'mitigation of wet oxidation deodorization - acid recovery of phenol or naphthenic acid - SBR process (treatment of alkali residue waste water process, and in 1998, in Shanghai A petrochemical enterprise has designed an industrial pilot plant which can effectively oxidize the organic sulfides and inorganic sulfides in spent lye to eliminate sulfuric acid and eliminate the stench gas emissions from the further treatment of the spent lye.However, Moderate wet oxidation has the disadvantages of incomplete treatment and harsh equipment requirements, but also because of excessively high temperature, carbon residue easily causes the pressure in the reactor and seriously affects the normal operation of the treatment device. Biological treatment of organic wastewater is convenient and fast, Mild, low energy consumption, less investment, no catalyst addition and operational safety, etc., get the general attention of researchers.
Alkali residue COD in the water generally tens of thousands to hundreds of thousands
Because of its complex composition, contains many refractory organic matter, therefore, it is necessary to explore a new method of deep treatment of alkali-based wastewater treatment plant. In this experiment, the activated sludge was domestically acclimated with the wastewater to be treated as the carbon source, and its effect on the treatment effect of alkali-based wastewater from refineries was investigated.
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