| Currently,the aquaculture has become an important part of the national economy.Pond aquaculture mode of promotion has accelerated the rapid economic development in our country,however,it has also caused many enviromnental and ecological problem.Such as aquaculture environmental degradation,waste of water source,heavy contamination,dilapiidated facilities and so on,which restricted the sustainable development of pond aquaculture heavily.The Aerated Biological Filter has been extensively used in treatment and reuse of sewage wastewater.It was characterized by its strong impulsion load resistance,small floor coverage,good treatment effect and simple structure.There is rarely reported of the B AF for aquaculture wastewater with low C/N ratio.To strengthen the denitrification effect,we added the anaerobic paragraph combined with aerobic paragraph of internal airlift loop bioreactor to compose the improved BAF with pre-denitrification treatment.The way of hanging bio-membrane and start-up process,the best operation parameters,understanding of migration and transformation mechanism of nitrogen compounds and the removal effect of typical antibiotics were studied in this paper.,which provides a new concept and reference for the recycle of aquaculture wastewater.The main contents and results are as follows:1.The experiments were started with the room temperature of 20?28?,DO(C/N reactor)?3mg/L and pH of 6.8?7.6.The biofilm culturing in this test was divided into two phases:nausea exposures phase(11d),gradual increase in the velocity of domestication phase(10d).The CODMn concentration in effluent was about 5mg/L,with the removal rate of NH4+-N was reached 58%and the removal rate of TN of about 62%,which represented the successful hanging film.2.The main factors affecting the operation efficiency of this process system are hydraulic loading,gas-water ratio,nitrification liquid reflux ratio and A/O volume ratio.The optimization parameters of the process were obtained by orthogonal test.On the condition that hydraulic loading value was 18 m3/m2·d,nitrification liquid reflux ratio was 100%,gas-water ratio was 6:1 and A/O volume ratio was 1.8,the reactor had a better processing effect.The removal rates of CODMn.NH4+-N and TN reached 44.08%,89.46%and 85.05%respectively,and the effluent values were 4.55mg/L,0.68mg/L and 0.87mg/L respectively,which can achieve the requirements of class III of Surface Water Quality Standards(GB3838-2002).The removal of TP was not ideal.3.During the stable operation of the best working conditions,the average removal rate of CODMn were 6%and 37.11%respectively in anoxic paragraph and aerobic paragraph,and the removal rate of NH4+-N were 51.45%and 37.41%,and the average removal rates of TN were 64.74%and 19.98%respectively.4.The process of denitrification in anoxic(DN)reactor includes:traditional denitrification(denitrifying bacteria takes organic compounds as carbon source),microbial assimilation,anaerobic ammonium oxidation and a small amount of heterotrophic denitrification.From the removal of TN and NH4+-N,it can be concluded that anaerobic ammonium oxidation and traditional denitrification are equivalent as for denitrification,with the total nitrogen removal is about 72.4%.5.The process of denitrification in aerobic(C/N)reactor includes:simultaneous nitrification-denitrification(SND)and microbial assimilation.And SND is significant with a high contributes to the total nitrogen removal rate.The ratio of NO2--N/NOx--N in effluent water of aerobic(C/N)reactor was always in the percentile and was low during the whole process,which indicates that there was no accumulation of NO2--N in this system.6.In this paper,the pre-treatment methods of extracting the sulfonamides antibiotics from the aquaculture wastewater by solid phase extraction was established and optimized.The BOJIN HLB solid phase extraction column was used in this study and the pH of the sample was adjusted to 3,and the flow rate was controlled at 4mL/min,with the ultrapure water as leacheate and 4ml methyl alcohol as eluant.7.The concentration and removal efficiency of sulfamethoxazole in the sewage of a large-scale farm in Changshu city of Jiangsu Province presented some seasonal change trends,with the influent concentration in autumn and winter was higher that in spring and summer.The highest level of sulfamethoxazole in autumn was 14.31 ?g/L,which was nearly 8 times of 1.63?g/L in summer.This study focused on comparing the treatment efficiency of each reactor in summer and autumn.The treatment efficiency of the anoxic DN reactor was negative in summer and autumn,with-14%in summer and-20%in autumn.The treatment efficiency of the aerobic C/N reactor was as high as 90%or more in summer and autumn,and summer is better than autumn slightly.The average concentration of sulfamethoxazole in the effluent was low,and the treatment efficiency of the process was stable. |
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