Study On The Biological Nitrogen Removal Process Of ABS Resin Wastewater

ABS resin is an important synthetic polymer, it is the polymer which obtained the largest output and the most widely used, currently. During the production process, a number of wastewater was coming out, which containing high concentration of organic nitriles and aromatic organic matter. The components of the wastewater are complex, and the wastewater are mixed with latex or latex resin powder and other solid materials, it is difficult to treat. The existing biological treatment processes for ABS resin wastewater primarily aim to remove organic matter in the wastewater, but lack of in-depth research on the total nitrogen(TN) remove effects. Therefore, this paper studied the denitrification potentials of ABS resin wastewater, impoldered a integrated biological nitrogen removal process with simple operation and stable effects, and the parameters of the process were optimized.ABS resin wastewater contains sufficient carbon source for its denitrification including both readily biodegradable and slowly biodegradable organics with different denitrification rates. For ABS resin wastewater with soluble chemical oxygen demand(SCOD) of 755.4-1043.3 mg/L and TN of 86.1-111.1 mg/L,the total denitrification potentials were from 95.4-144.6 mg/L(NO3--N). Organic nitriles in ABS resin wastewater, can be degraded significantly with generating of ammonia nitrogen(NH4+-N) during the denitrification process, they were important carbon sources for denitrification. The aromatic cycles of aromatic organic matter in the wastewater were not destroyed significantly under denitrificantion conditions while they were destroyed quickly during aerobic conditions.Toxic organic matter in ABS resin wastewater, including organic nitriles and aromatic organic compounds, can be removed effectively in the impoldered integrated bioreactor. When ABS resin wastewater was treated under the mode of anoxic/oxic(A/O), the nitrogen removal effect was better than that was treated under the mode of micro-aerobic. Under the optimized mode of A/O [hydraulic retention time(HRT) of the anoxic zone was 7 h, HRT of the oxic zone was 21.3 h, the concentration of dissolve oxygen(DO) in the oxic zone was 1 mg/L, the return ratio of the mixed liquor was 4], the COD concentration of effluent complied with the Class B of Integrated Wastewater Discharge Standard(GB8978-1996), the TN and NH4+-N concentrations of effluent satisfied the first A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).The research results of microbial morphology showed that microorganisms which were mainly bacillus and coccus, were adhered on the surface of the activated sludge. The flocs of the activated sludge were tight, and a low number of filamentous bacteria were found. Various types of protozoa were found in the activated sludge. The analyses of fluorescence in situ hybridization(FISH) of the activated sludge showed that the proportions of ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) were relatively high, ensuring that the bioreactor had the advantage of stable nitrogen removal effect.