| Livestock wastewater was a kind of complex pollutant, with high organic matter, high ammonia and high phosphorus, and it had become a major source of water pollution in the exurb and rural areas. In this study, the combination of UASB-SBBR process was used to treat livestock wastewater. The start-up, steady operation and condition optimization of the system were detailed studied.The results showed that a stable UASB-SBBR process performance was achieved after running continuously for103d. In the steady operation stage, COD, NH4+-N, TN and TP of the effluent were234.3mg·L-1,14.8mg·L-1,34.9mg·L-1and26.3mg-L-’respectively, and the removal rate of these contaminants could achieve97.1%,95.7%,90.0%and28.9%respectively.In the steady operation of UASB, under the conditions of temperature35℃, reflux ratio3:1and volume loading8.1kgCOD·(m3·d)-1, the removal rate of COD was85.6%. The volume gas production rate arrived at2.2L·(L·d)-1, the gas production of consumption unit of COD was316.9ml·g-1, and the methane content was 70.5%, VFA concentration of effluent was204.0mg·L-1and the pH was not lower than6.9. Then, the effects of influence factors for UASB such as volume loading, reflux radio and temperature on the treatment performance were studied. The results showed that when the volume loading was8.1kg COD·(m3·d)-1], temperature between25～35℃and reflux ratio between3:1～5:1, it could improve the percentage of COD removal rate and keep the UASB stable operation.By cultivating the microorganism of SBBR, the reactor initially had the capacity to treat biogas slurry of livestock wastewater. Under the conditions of room temperature, the replacement rate of wastewater20%, the effluent removal rates of COD, NH4+-N, TN and TP were78.7%,95.6%,89.6%and25.5%, respectively.In the test on DO concentration for SBBR, the results showed that the influence of DO on the removal rate of COD and TP were very limited, while it mainly influenced the removal rate of NH4+-N and TN. DO could affect the result of nitrification and denitrification through influencing the ratio of aerobic area and anaerobic area in the biofilm reactor. When the average concentration of DO was1.4mg·L-1in aerobic stage, the removal rates of NH4+-N and TN were95.4%and89.4%. After the aerobic stage, the concentration of NO2-N and NO3-N were21.2mg·L-1and8.0mg·L-1respectively, there was an obvious shortcut nitrification phenomenon in the reactor. On the other hand,69.8mg·L-1of TN was removed in the whole cycle, but42.7mg·L-1of TN (61.2%of the total TN) was removed in the aerobic stage, which showed the reactor achieved a higher degree of SND.After the start-up stage of SBBR, the species, species number and dominates of microorganisms in the biological were different from the suspended sludge. There were a lot of nitrobacteria and denitrifying bacteria in the biological, and meanwhile, phosphorus accumulating bacteria mainly existed in the suspended sludge. |
PDF Full Text Request