Large Variability of Thickened Sludge Quality at a Municipal Plant makes n=1 Experiment with Digestion Invalid: n=2 with Pilot-Reactor Experiment shows Excellent Reproducibility
Changes in sludge handling practices in full-scale wastewater plants are often by necessity evaluated without the use of replicates (n=l).For example,a study evaluated the increased digestibility of thickened sludge and the resulting effect on biogas production yields.Here,we investigated the anaerobic treatment characteristics of fresh,thickened sludge (consisting of primary,secondary,and waste activated sludge) at a municipal wastewater treatment plant.We also added an experiment to evaluate the use of the Fenton reaction to increase digestibility.To accomplish this,two identical continuously stirred anaerobic digesters (CSADs),with an effective volume of 45 L each,were operated in parallel at mesophilic conditions (32℃±1) for an operating period of 280 days (n=2).We also included anaerobic settlers to mimic the full-scale plant.We fed fresh,thickened sludge in the digesters once every other day.We observed very large fluctuations in biogas production due to ever changing characteristics of the thickened sludge.However,the two systems performed almost identically.In addition,despite these variations,both systems showed similar results in terms of chemical oxygen demand (COD) removal efficiency and biogas production,achieving 63.75±2.9% and 62.1±3.2% for COD removal,and 0.280 L CH4.g volatile solids (VS)-1 and 0.279 CH4.g VS-1 methane yield for experimental (with Fenton) and control (without Fenton) CSADs,respectively.These results also indicated that the use of a Fenton reaction did not affect biogas production.We hypothesize that the reported increase in biogas productivity from the Fenton reaction in a full-scale system may be an artifact of these large fluctuations between days and seasons,and that this artifact is particularly difficult to identify (n =1).
Anaerobic digestion thickened sludge wastewater treatment Fenton reaction biogas
Ahmet E.Uman Joseph G.Usack Jose L.Lozano Largus T.Angenent
Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA;C Ithaca Area Waste Water Treatment Facility, Ithaca, NY USA 14853
国际会议
The 15th IWA World Conference on Anaerobic Digestion( 第15届IWA世界厌氧大会)
北京
英文
303-306
2017-10-17（万方平台首次上网日期，不代表论文的发表时间）