BIOCHEMICAL METHANE POTENTIAL OF WASTEWATER CONTAINING ZINC

Abstract

The strength of wastewater is measured by parameters such as BOD, COD, TOC etc. Anaerobic biodegradability is assessed by BMP of wastewater. BMP is a measure of sample biodegradability. It is anaerobic counterpart of aerobic BOD. BMP depends on nature of organic substance, presence of metal, ions, sulfates, phosphates, buffering capacity, C:N ratio etc. Trace quantity of metal ions is required as nutrient, however, they are toxic if present in large quantity and affect the BMP values. Wastewater from industries such as Viscose Rayon contain zinc, as well as sulfate, sugar industry contain sulfates and Cr. in wastewater from tannery. Before, arriving at suitability of anaerobic treatment process it is essential to' evaluate BMP. Keeping this in view, technique to assess BMP values was generated in Environmental Engg. Lab of Civil Engg. Deptt., University of Roorkee, Roorkee. Results of few experiments indicated that the presence of zinc in certain concentration range stimulates the anaerobic digestion measured by its activity. It, therefore, necessitated to study the effect of added zinc as ZnSO4 , ZnCl2 and ZnS on acidification and also effect of Zn (i.n the form of ZnCi2 and ZnS04) on methane genera-tion. Studies have been carried out on sy11, wastewater prepared by diluting molasses.. Optimum C:N ratio of 30:0.5 was maintained by adding urea to the waste during acidogenesis and by. having COD Of wastewater to be 3660 in case of BMP assay. All the works were carried out at a temp. of 30°C Acidification was monitored by Measuring volatile acid, COD, , and BMP was monitored by measuring total gas collected and percentage of methane in the gas. Also, an atteffipt has been made to correlate BMP5 and BOD5 of this wastewater.