Experiment on pretreatment of waste water from bamboo heat treatment by combination of iron-carbon micro-electrolysis and Fenton method

Abstract

Abstract The chemical oxygen demand (COD) of waste water from bamboo heat treatment is mainly organic macromolecule compound which degraded from hemicellulos, lignin and extractives. COD is toxic to aquatic organism and human body and very difficult to degrade. The paper studied the possibility of pre-treating the bamboo heat treated waste water (BHTWW) by combination of iron-carbon micro electrolysis and Fenton method. Orthogonal experiment was designed with 3 factors: the initial pH value, retention time and H2O2 dosage, and carried out with a dynamic sampling device with 2:1 iron carbon ratio. Results showed that the iron-carbon micro electrolysis and Fenton were proved to be a potential method in pre-treating BHTWW, and the optimum parameter should be pH 3.0, 40 min residence time and 0.5 % H2O2. After pre-treating, the removal rate of COD was 60.29 %, and B/C (biochemical oxygen demand after 5 days (BOD5)/COD increased from 0.037 to 0.32, the biodegradability was significantly improved. During the pretreatment, the nutrients in BHTWW had been oxidized, the double bound, conjugated double bond in guaiac lignin were opened or broken and degraded into more small molecular, nutrients such as TOC (total organic carbon) content, total nitrogen and total sugar content all decreased which all contributed for the increase of B/C. The microstructure of activated carbon appeared broken and collapses after pretreatment which indicated that they were eroded or involved during the micro electrolysis reaction.