| Acrylic wastewater belongs to refractory industry wastewater.It is a major challenge to deal with acrylic wastewater,because its composition is complicated.The key point in the treatment for the acrylic fibre wastewater is particles of white oligomer which caused poor biodegradability due to these substances are suspending in the wastewater and hard to be precipitated.Using the pretreatment of biological adsorption, this paper researched the effects of sludge concentration, adsorption time and regeneration time of adsorption on the adsorption capacities. In addition,the test studied the factors in the process of denitrification based on the the results of SBR small test, mainly concentrated the basicity, phosphorus sources, mixture flow and hydraulic retention time on the effects of the denitrification, and obtained the optimum experiment conditions, for acrylic production enterprises to provide the technical support for wastewater treatment. The experimental results showed that:(1) The best condition of activated sludge adsorption Small test.The primary results showed as below, the COD removal rate reached 26.89% of wastewater treated by biosorption when the sludge concentration was 2.246 g?L-1,adsorption time 30 min, regeneration time 8.0 h. It was demonstrated that after added the Na+, Mg2+, Al3+,the wastewater removal rate of COD was improved,and the optimum concentration for 10-2 mol?L-1.Besides,Al3+ had the best effect on the promotion of sludge adsorption,it could make the removal rate of COD of wastewater increased from 32% to 51.3%.Acidic or weak alkaline condition could promote the effect of sludge adsorption,particularly when the pH was 1 or 9,the removal rate of wastewater COD reached 53.7% and 53.7%, respectively. The best condition of ammonia nitrogen removal rate was acidic condition, when the pH was 1, its removal rate reached 46.8%.(2) The pilot-scale test of activated sludge.The results demonstrated as follows,the optimum condition was temperature 25℃, pH 6.8 ~ 8.5, dissolved oxygen above 2 mg?L-1, adsorption time 30 min,optimum reflux ratio 75%, the adsorption effect was best under these conditions, and the COD removal rate was 30.3%.Biosorption for acrylic fiber wastewater can be a little change on biochemical and effect of ammonia nitrogen removal.Acrylic wastewater which had been pretreated by biological adsorption after biochemical treatment, its averages of COD and ammonia nitrogen concentration were lower than that without pre-treated by biochemical adsorption, the values were respectively 8.8% and 17%.(3)The test of nitrogen removal. When the inlet water temperature was 28~30℃, pH 6.8~8.8, DO 2.0~4.0mg/L, the amount of disodium hydrogen phosphate 800 g/d, sodium bicarbonate 4800 g/d, the ratio of mixture reflux 200%, hydraulic retention time 31.68 h, the removal rate of activated sludge process for acrylic fiber wastewater was higher than normal activated sludge process,the removal rate of COD was 57.8%, the removal rate of ammonia nitrogen was 55.3%, and the removal rate of total nitrogen was 12.1%. According to this, increasing phosphorus source,basicity, mixture flow, hydraulic retention time of acrylic fiber wastewater could improve the denitrification effect by activated sludge process.Biological adsorption as pretreatment process for acrylic wastewater, has the fast response time, reactor volume is small, low running cost, hard dissolved in the waste water and biodegradable organic removal efficiency good advantages;Biological adsorption method can remove the 30% CODcr in the acrylic fiber wastewater by the function of biological adsorption, created favorable conditions for the subsequent biochemical treatment, can be used as acrylic wastewater pretreatment process.In addition, in the biochemical process of acrylic wastewater, increase the content of phosphorus and basicity, the mixture flow back, and increasing hydraulic retention time can improve the denitrification effect of acrylic fiber wastewater by ctivated sludge process, make the water get to discharging standard. |
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