Enhanced The Ammonification and Biotreatability of High-Strength Organic Nitrogen Wastewater by Pre-Ozonation Process

• Main Authors: Cho, Bo-Chuan, 卓伯全
• Other Authors: Chang Cheng-Nan
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/90597408682201467161

碩士 === 東海大學 === 環境科學系 === 85 === The ABS (Acrylonitrile-Butadiene-Styrene) industry is booming in South Eastern Asian countries and these countries are becoming the leading producers of ABS in the world. Major raw materials for manufacturing ABS resins include acrylonitrile and styrene; both are toxic and highly resistant to biological degradation. Field data show that the ABS wastewaster contains high concentrations of COD, organic nitrogen, and high ratios of TKN/ TOC and Org-N/COD as well as high alkalinity of up to 1,500 mg/L as CaCO3The results indicate that degradation of organic nitrogen follows zero order reactions for all acrylonitrile samples. Samples with lower initial pH*s have higher degradation rates as seen by their higher reaction rate contants. Based upon the observed zero-order degradation of the organic nitrogen, the time needed to complete 50% of the degradation reaction (t1/2) for each sample can be estimated. The calculated t1/2 values is 18.87 min for the sample with the lowest initial pH of 4 and decreased with inNernst equation is used to model the acrylonitrile oxidation process. The modified Nernst model (ORP universal model) may be applied to simulate the variation of ORP values and thus can be used for controlling a proper ozone contact time during the decomposition of acrylonitrile. The fluctuate dORP/dt profiles were measured during the polarization stage of styrene. At the completion of polarization stage, the dORP/dt profiles had a relatively flat fluctuation. After the ozonation pre-treatment, styrene In the field ABS wastewater study, we applied ozonation to both raw and filtered ABS effluent and investigated the profiles of pH, ORP, BOD5, COD, DOC, and organic nitrogen. Both raw and filtered samples were adjusted with the COD-ozone rates, i.e. mgCOD/mgO3( g).L, 19, 38, 56, and 75 for raw and 11, 22, 33, and 44 for filtered ABS wastewater. The raw ABS contains tremendous suspended solids, which may be part of the by-products of ABS polymer fragments. The SS portion may interfere with the penetration of In raw ABS wastewater ozonation study, the organic solids were decomposed by ozone and may be released into solution as either COD or DOC. At the low COD-ozone loading rates (19 and 38 mgCOD/mgO3(g).L), the COD can be decomposed at the rate of 21% and 53% respectively. Ozone may increase the ratio of BOD5/COD, which may imply the biodegradability of organic matter with the increase from 44% to 65%. The organic ABS polymer was retardant to biomass before ozonation and had a low BOD5/COD ratio. In the casThe filtered ABS, i.e. that which contains only soluble matter in solution, can react with ozone directly and without any interference. This approach may improve the ozonation efficiency and save operation cost, yet it needs more process to take SS from it. In the case of low COD- ozone loading (11 mgCOD/mgO3(g).L), the COD (and DOC) reduction rate can only increase from 17% to 39% (and 16% to 22%). After the conversion of both COD and DOC, the BOD5/COD ratio increases to 2.1~4.3 times more than that of raAmino acids, which are released from the complex mixture of ABS polymer and one of the intermediate products, are the main portion of organic nitrogen found in solution. The lower COD-ozone loading rate and longer reaction time may generate more amino acids in organic nitrogen portion. In solutions, it is believed that organic nitrogen is difficult to be decomposed to ammonia nitrogen. The amino acids to organic nitrogen ratio may increase from 8% to 52%~96% after ozonation. The output amino acids belongThe COD, DOC, BOD5, Org- N, and total amino acids (TAA as N) concentration variation of filtered ABS sample reveals a relationship between chemical items and ORP levels. At initial low ORP level, release was seldom observed, but when the ORP reached a high level (450 mV), the COD decreased and BOD5 increased. The observed BOD5/COD variation of raw ABS effluent also reveals a similar stage-wise release pattern. For low COD-ozone loading ( 19 mgCOD/O3(g).L ) case, it has a sudden increase at the ORP value o