自搅拌厌氧折流板反应器连续处理猪场废水的效果

Continuous anaerobic treatment of swine wastewater by using self-agitation anaerobic baffled reactor

该研究以猪场废水为处理对象,采用自搅拌厌氧折流板反应器(self-agitation anaerobic baffled reactor,SaABR)开展200 d的连续中温厌氧消化试验,考察在水力停留时间(hydraulic retention time,HRT)3、2、1和0.5 d梯度缩短的过程中,SaABR截留微生物的效果以及反应器的产气性能、稳定性和污泥比产甲烷活性(specific methanogenic activity,SMA)。同时,该研究还开展了全混式反应器(completely stirred tank reactor,CSTR)78 d的连续对比试验。试验发现,SaABR具有良好的截留微生物的作用,在HRT 3 d时SaABR第1至第4取样口污泥挥发性固体(volatile solid,VS)浓度分别为10.2、4.1、44.2和2.5 g/L,而CSTR污泥VS质量浓度仅为2.6 g/L。较高的微生物量显著提高了有机物的降解率并降低了出水的有机酸浓度。随着HRT的缩短,SaABR的降解率也呈现下降。在HRT1d时,SaABR的单位VS产甲烷率为0.43 L/g,即使在HRT缩短到0.5 d时,仍然可实现稳定的发酵产气(单位VS产甲烷率为0.24 L/g),而CSTR反应器由于微生物洗出不能在HRT 1 d时连续产气。该研究的结果显示,SaABR反应器所具有截留微生物的良好特性,为养殖粪水的处理提供参考。

With the development of pig industry in China,environmental pollution from such development has become more and more serious.One of the most important problems of pig breeding is the wastewater treatment.Swine wastewater is characterized by the high concentrations of organic matters.Anaerobic digestion has been regarded as a promising technology for swine wastewater treatment to remove the high-concentration organic materials.At the same time,renewable energy in the form of biogas was produced through anaerobic degradation.Previous studies have reported that anaerobic baffled reactor(ABR)can achieve good performance in treating swine wastewater.However,due to the absence of agitation system,the mass transfer is an ABR is unsatisfactory.In order to improve the performance of an ABR,the self-agitation anaerobic baffled reactor(SaABR)was proposed.In the SaABR,a U tube was assembled inside the reactor.SaABR is previously studied in the anaerobic treatment.However,fewer its application in treating swine wastewater was found.The current study therefore investigated the performance of a long term operated SaABR in treating swine wastewater.The total and working volume of SaABR in this study were 16 and 10 L,respectively.Anaerobic treatment of swine wastewater for a period of 200-day was continuously conducted.Mesophilic condition was maintained at 37℃while hydraulic retention time(HRT)was gradual shortening from 5,3,2,1,to 0.5 days.The effects of HRT on the biomass retaining,biogas gas production,process stability,and specific methanogenic activity(SMA)was investigated.At the same time,in this study,we also conducted a 78-day continuous experiment by using a parallel continuous stirred tank reactor(CSTR)as control test.The results derived from this study indicated that SaABR significantly retained high biomass concentration.At the HRT 3 d period,the volatile solid(VS)concentration of the first to fourth sampling ports of SaABR was 10.2,4.1,44.2 and 2.5 g/L,respectively.The concentration of VS in the CSTR was as low as 2.6 g/L.The higher microbial biomass significantly increased the degradation efficiencies of organic and reduced the VFAs concentration of SaABR effluent.The degradation efficiency of SaABR also decreased with the shortening of HRT.The specific methane yield of the SaABR was 0.43 L/g at the HRT 1 d period.At the HRT 0.5d period stable biogas production can still be achieved.Through the long term experiment,an increase of volumetric gas production rate was observed:0.85,1.14,1.62 and 1.71 L/(L·d)at HRTs 3,2,1 and 0.5 days,respectively.Specific methane gas yield decreased from 0.69 to 0.24 L/g when HRT was reduced from 3 to 0.5 d.These values were slightly higher than results of a previous study using ABR treating swine manure at 40℃,which reported specific methane yield was 0.59 L/g.The CSTR ceased to produce biogas at HRT 1 d due to the washout of biomass.At HRT 3 d period,the sludge SMA from the first to the fourth sampling port were 116,97,44 and 85 mL/(g·d),respectively.Conclusively,the results obtained in this study showed that SaABR had the advantages of retaining high biomass and would be a promising technology for the anaerobic treatment of swine wastewater.