| Alcohol waste water producing in the process of alcohol production,which mainly includes the alcohol waste after distillation of fermented mash,the washing water of the equipment and the cooling water in the production process.Cassava and molasses are the two raw materials for alcohol production,the corresponding alcohol wastewater is cassava starch alcohol wastewater and molasses alcohol wastewater respectively.Alcohol wastewater has a high content of organic matter and suspension,low p H,large emissions and difficult treatment,which have brought great environmental and economic pressure to alcohol production enterprises.It is urgent for alcohol production enterprises to seek the technology that can effectively treat alcohol wastewater.As a sustainable wastewater treatment method with high efficiency,low operating cost and can produce biogas,anaerobic biological treatment technology has become one of the preferred methods for industrial organic wastewater treatment.The feeding pattern has an important effect on the anaerobic treatment of wastewater and is considered to be one of the important factors affecting the anaerobic treatment efficiency of wastewater.At present,there is less research on the effect of feeding pattern on industrial wastewater of anaerobic treatment,and mainly in the stable operation of constant organic load.In this study,the effects of feeding patterns on anaerobic treatment of alcohol wastewater was studied by combining gradually increasing organic load method.The purpose of this study is to optimize the treatment process of alcohol wastewater,improve the treatment efficiency,and provide reference for anaerobic treatment of other wastewater.In this study,anaerobic treatment of cassava starch alcohol wastewater by continuous,semi-continuous and pulse feeding patterns was studied firstly.Then,on the basis of the study on anaerobic treatment of cassava starch alcohol wastewater,the time interval of the feeding patterns was optimized.With the activated sludge which was anaerobic domestication by cassava starch alcohol wastewater as seeding sludge,the study on the anaerobic treatment of molasses alcohol wastewater by continuous,semi-continuous and pulse feeding patterns was carried out.Finally,at the lab scale,the resistance of anaerobic activated sludge domesticated by different feeding patterns under low p H influent,high OLR?organic loading rate?,high ammonium and high sulfate shocks was investigated.The response of the microbial community in three kinds of anaerobic activated sludge to four tress shocks was also studied.The main results are as follows:1.In the anaerobic treatment of cassava starch alcohol wastewater by three different feeding patterns,continuous feeding and semi-continuous feeding reactors can lift the load faster than pulse feeding reactor,and can reach higher organic load.Under high organic load,the dissolution chemical oxygen demand?SCOD?removal rate and biogas production of semi-continuous feeding reactor was significantly higher than that of continuous feeding reactor with the same influent organic load.Compared with the continuous feeding reactor,the maximum SCOD removal rate of the semi-continuous feeding reactor was23.20%higher and the maximum gas production was 95.7 L/2d higher.The concentrations of volatile fatty acids?VFA?and ammonia nitrogen?NH3-N?of semi-continuous feeding reactor in the whole process of anaerobic digestion were lower than those in continuous and pulse feeding reactors.With the development of anaerobic digestion,the diversity of bacteria and archaea in each reactor kept changing,and the abundance of dominant bacteria and methanogens in the semi-continuous feeding reactor was higher than that in the other two reactors.According to the performance parameter results of the three reactors,semi-continuous feeding is the best pattern,followed is continuous feeding,and the worst is pulse feeding.2.In the anaerobic treatment of molasses alcohol wastewater by three different feeding patterns,after the reactor was in stable operation,the SCOD removal rate of each reactor treating the normal molasses alcohol wastewater reached about 80%when the influent SCOD was lower than 24,000 mg/L(OLR=6.4 mg.L-1.d-1).The performance of each reactor was seriously affected when the influent SCOD was higher than 45,000 mg/L(OLR=12 mg.L-1.d-1),methane content of biogas and SCOD removal rate significantly decreased,while VFA and NH3-N concentration significantly increased.The analysis of microbial diversity showed that with the progress of anaerobic digestion,the diversity of bacteria and archaea in each reactor was constantly changing,and the structure of bacteria and methanogens had similar changes,but the abundance of dominant bacteria and methanogens was different.Based on the performance parameter results of the three reactors,it was found that there was no significant difference in the performance of the three reactors in the anaerobic treatment of molasses alcohol wastewater,but the performance of the pulsed feeding reactor was greatly affected by the characteristics of the wastewater and the high organic load.3.The anaerobic reactor can be started quickly and stabilized by gradually increasing the influent organic load in a small range.In the process of anaerobic treating cassava starch alcohol wastewater,SCOD removal rate of continuous and semi-continuous feeding reactors was above 70%in the initial start-up period,SCOD reached about 80%in the stable period,but the SCOD removal rate of pulse feeding reactor fluctuated greatly.In anaerobic treatment of molasses alcohol wastewater,the SCOD removal rate of the anaerobic reactors with different feeding patterns all reached about 80%in the early start-up period and remained stable.4.The study of anaerobic activated sludge resistance showed that the anaerobic activated sludge domesticated by three feeding patterns had good resistance to low p H influent and high sulfate shocks,and poor resistance to high OLR and high ammonium shocks.The anaerobic activated sludge domesticated by semi-continuous feeding had the best resistance to high OLR shock,followed by pulse feeding,and then continuous feeding.There was no significant difference in the resistance of the three activated sludge to low p H influent,high ammonium,or high sulfate shocks.5.The microbial diversity analysis results of the activated sludge under four stress shocks indicated that the differences in the microbial population,diversity and the relative abundance of specific functional microorganisms in the activated sludge might be responsible for the differences in the resistance of anaerobic activated sludge.The feeding pattern had a certain influence on the anaerobic treatment efficiency,the characteristics of activated sludge and the functional microbial community.The influence degree varied with the type of wastewater,OLR and the frequency of the feeding pattern.In general,semi-continuous feeding pattern was better.The results deepened the understanding of the effects of different feeding patterns on the anaerobic treatment of industrial wastewater,provided reference for the selection of the feeding pattern of anaerobic treatment of wastewater,and revealed the response mechanism of the associated microorganisms in the anaerobic treatment of wastewater,which guided significance for the optimization of the anaerobic treatment process of wastewater. |
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