Recovery of nutrients and water from anaerobic digestion effluents by electrocoagulation using Fe and Al electrodes
The liquid effluents (or digestates) from anaerobic digestion (AD) often have high levels of biological oxygen demand (BOD) which may be hazardous to the environment if not removed before disposal.Digestates are also commonly rich with elements (e.g.N,P,Fe,Zn,Co,Ni,and Mn) that have the potential for use in agricultural fertilisation of arable land.Therefore,extraction of fertilising nutrients,reduction of BOD and recovery of water is desirable for environmental and commercial aims.Electrocoagulation (EC) is a technique used to separate contaminants and water in liquid effluents.EC is driven by an electrical circuit containing a metal anode and cathode in contact via an aqueous stream of effluent.The flow of electricity around the circuit causes corrosion of the anode and subsequently metal ions enter the effluent.The resulting hydroxides bind to dissolved and suspended contaminants and remove them from solution via adsorptive and co-precipitation mechanisms.Simultaneously,contaminants are removed by cathodic reactions that cause their deposition on the electrode surface or physical flotation by the evolution and rising of H2 molecules.Fe and Al are desirable electrode materials for EC because of their abundance in environment,cost and valences.EC has a number of advantages over conventional chemical dosing applications such as reduced secondary contamination,increased removal efficiency and a lower risk of environmental pollution.The authors are working alongside Elentec Ltd to apply bespoke EC equipment to treat digestates derived from lab-scale and full-scale AD of farm slurry,food waste and sewage sludge.The aim is to compare the use of Fe and Al for recovering nutrients and water from AD effluents.Our work has demonstrated that EC using Fe and Al electrodes can successfully cause the sedimentation of up to 90.7% and 89.0% of suspended P in sewage sludge digestate,respectively.
Electrocoagulation Anaerobic digestion Nutrient recovery Digestate
M.Reilly D.Tito B.Richardson S.A.Tassou M.K.Theodorou
Agricultural Centre for Sustainable Energy Systems (ACSES), Harper Adams University, Newport, Shrops Institute of Chemical Process Fundamentals of the CAS, Rozojova 135/1, 165 02 Prague, Czech Republic Institute of Energy Futures, Brunel University, Uxbridge, Middlesex, UB83PH, UK
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
681-685
2017-10-17（万方平台首次上网日期，不代表论文的发表时间）