Study On Landfill Leachate Pretreated By Anaerobic Sequencing Batch Reactor

Landfill leachate is a kind of organic wastewater with high concentrations of pollutants,complicated composition and properties of volatile.The treatment of it is very difficult. Currently, as part of the leachate treatment process, anaerobic pre-treatment plays a key role in the treatment effect. In this paper, landfill leachate was pretreated by the anaerobic sequencing batch reactor (ASBR) to cut down its organic load. Based on basic mechanism of the reactor, three lab-scale reactors were quickly started. Then its effect on the leachate treatment has been analysed, the characteristics of removing the small organic molecules in leachate have been explored, the degradation rule and dynamics of the nonbiodegradable macromolecular organic pollutants in leachate have been researched, and the characteristics of removing the organic molecules in each segment have been examined.Under optimum conditions, two ASBR devices were continuously run to study the effect of the leachate treatment, also investigated the reliability ASBR process.The simulated42d continuous running test indicated that ASBR had a good and relatively stable effect on treating the organics in leachate, but the removal effect on ammonia nitrogen was not obvious. The removal rate of COD remained at around95%, VFA was about2.2mmol/L,and the accumulation phenomena didn’t appear, alkalinity maintained at the range of2500-3900mg/L, pH value ranged from7.5to7.8, and ammonia nitrogen was about280-370mg/L, which was very close to the ammonia nitrogen concentration of influent. Using the ASBR pretreatment process can effectively reduce the organic load in leachate, but in the subsequent process design, the treatment of ammonia nitrogen in leachate needs to be strengthened.Using GC-MS technology to identify organic pollutants component and discuss the removal characteristics of various pollutants by ASBR. GC-MS analysis showed that15kinds of small organic molecules whose molecular weight ranges from20to450in leachate have been detected, eight kinds of the organics have not been detected after treating by the ASBR, the removal rate reached to100%. The simulated humic acid wastewater experiment indicated that the influent nonbiodegradable macromolecular organic pollutants ranged from618.7mg/L to2210.02mg/L have no impact on the metabolic activity of microorganisms in ASBR, and ASBR method can greatly degrade biodegradable organic macromolecules in3hours. The most excellent condition of degradation was in a good domesticated sludge condition, the initial concentration of humic acid was918.0mg/L.The degradation of nonbiodegradable macromolecular organic pollutants conformed to the first order reaction kinetics equation.Analysis of molecular weight cut aimed at analyze the removal characteristics of organic matter in different range of molecular weight indicated that ASBR had a removal advantage to the small molecular weight organic pollutants (the molecular weight is less than6×103) and large molecular weight organic pollutants(the molecular weight ranges from50×103to100×103), the average removal rate reached to95%or more.According to the preliminary analysis of the UV254in influent and effluent, ASBR had a better removal efficiency to the nonbiodegradable macromolecular organic pollutants whose molecular weight ranged from50×103to100×103in leachate, and the removal rate reached to98.8%.Studies showed that the leachate pretreatment by ASBR is effective, and a highly efficient removal of organic pollutants in leachate can be achieved, but it does not have advantage to remove ammonia nitrogen. This article possesses a guiding significance and reference value for the engineering positioning and engineering applications of ASBR, as well as landfill leachate treatment and pollution control.