Evaluation of Performance of Sequential Membranes Used in Pilot Scale Biogas Plant: A Case Study for Laying Hen Manure

Abstract

Poultry sector is a very important business activity in all over the Europe, especialy in Turkey and accordingly there is significant amount of waste disposal problem. One of the environmental assesment options for the use of this waste is environmentally friendly biofuel production such as biomethane. High nitrogen content is one of the important challenges to transform chicken manure to biofuel. For this reason, significant amount of dilution water is required in the systems using manure as mono substrate and thereby very large storage volumes (storage time 4-6 months) are needed for the enormous amount of effluent after anaerobic digestion process. These two subjects are threatening the economic viability of the biogas production. Furthermore, need for dilution water is an economic burden to the businesses in countries where the water scarcity is a serious concern. On the other hand, integrated use of membrane system offers possibility of using the digestion effluent as dilution water over and over where nitrogen is removed selectively by membrane assisted biogas reactor configuration. In this way, significant economy could be provided in the overall project budget by eliminating the final storage needs as well as water saving. For this purpose, the performance results of a pilot plant scale membrane system consisting of micro (MF), ultra (UF), nano (NF) and reverse osmosis (RO) membranes are presented in this study to be used in real scale applications. The feasibility of continuous reuse of digestate as fresh feed water was suggested. For this purpose, NF90 and X20 type membranes were found to be most effective ones for the recovery of ammonium (88% and 98%) from the digestate,