| Dairy wastewater is characterized by large fluctuations in water volume,high organic nitrogen content,high concentration of organic matter,and good biochemical properties.The organic matter in dairy wastewater includes several types such as fats,proteins,sugars,etc.Most of these organic matters can be biodegraded and are suitable for biological treatment.But when choosing the process,we should choose those that are not easy to produce sludge expansion as well as the nitrogen removal effect.While meeting the water quality,we should also consider about the cost issue.Any one single process can’t meet several conditions,so it is proposed to use a composite process,through two or more processes.The combination is more economical and resource-efficient while meeting the discharge conditions.This study takes dairy production wastewater as the object of research,and considers the advantages and disadvantages of each process combination,and seeks a highly efficient,lowconsumption,low failure combination to deal with dairy wastewater.The anaerobic reactor used in the study is improved on the basis of the existing anaerobic technology,which is mainly reflected in two aspects: 1.Reducing the height to diameter ratio to reduce of power consumption in outward flows.2.Adding filter plate in the reactor can make the distribution water uniform and mud water mix more fully.It also increases the bio-adhesion area and enhances the bio-efficiency.The experiment mainly investigates the effects of the removal of pollutants by hydraulic retention time(HRT),COD load,temperature,and external reflux ratio reaction.The results showed that the hydraulic retention time and temperature had the most significant effect on the reactor.When the condition is a hydraulic retention time of 16 h and temperature controlled at25°C.～30°C,inlet water p H controlled above 7,and the external reflux ratio R=2,the removal of COD is above 90%.The concentration of ammonia and nitrogen increased significantly after the anaerobic reactor treatment.The removal of ammonia nitrogen was 77.5% after subsequent treatment and the removal of COD increased to more than 98%.The removal of BOD was investigated in the optimum process parameters during operation of the feed water under three loads: low,medium and high.The removal rates of BOD were 46%,50.97%,53.45%.The removal rates of N-BOD were38.6%,33.04% and 27.85%.It was found that the BOD removal rate increased with increasing load,while the N-BOD removal rate decreased.The carbon and nitrogen transport in the water were analyzed and measured,and the effects of different loadings on the carbon and nitrogen transport were investigated respectively.Microbial changes in the sludge before and after reactor startup were studied.The sludge was analyzed by scanning electron microscopy,and it was found that not only the morphology of the sludge changed,but also the abundance of microorganisms increased significantly.The high flux analysis of microorganisms before and after the stable operation of the reactor revealed that the proportion of methanogenic bacteria in the stable period increased.The gas production analysis was carried out and it is also found that the proportion of methane in the gas produced increased.From the above results we can determine whether the reactor is in good operation status from a microscopic point of view. |
PDF Full Text Request