Effect of Chemically Pretreated Water Hyacinth Co-Digested with Poultry Litter in Anaerobic Digestion

Abstract

This study focuses on the biogas production from water hyacinth (WH) while co-digested with poultry litter (PL) through bio methanation. The high content of hemicelluloses and cellulose present in the water hyacinth demands the need for pretreatment to enable the rapid anaerobic decomposition of the organic matter and resulting in improved process rate and biogas yield. Water Hyacinth is chemically pretreated using NaOH and lime to achieve partial disintegration of very long unbranched fibrils composed exclusively of glucose, with hydrogen bonding. The chemical disintegration of hemicellulose is achieved initially by hydrating the chopped WH in the ratio of 1:1. The hydrated WH is added with 1% by weight of NaOH and lime separately in batches. The digestion was performed in four fixed dome batch type digesters namely with raw WH, Lime pretreated WH+PL, and NaOH pretreated WH+PL and co-digestion of WH with PL. The digestion was carried out at mesophilic anaerobic condition and the pH is maintained at near neutral range for a hydraulic retention time of 21 days. As a result, it is observed that there is an increment of 51.57 % in biogas yield while codigesting with lime and more interestingly the digester with NaOH pretreatment results in 51.57% incremental biogas yield compared to the raw WH.