INVESTIGATIGATING THE EFFECTS OF MICROWAVE AND THERMOCHEMICAL PRETREATMENTS ON CONVERSION OF SLUDGE INTO WATER SOLUBLES TO IN CREASE THE BIOGAS YIELD

6th International Scientific Conference - SGEM2006, www.sgem.org, SGEM2006 Conference Proceedings/ ISBN: 954-918181-2, June 12-16, 2006, Vol. 1, 119-128pp

ABSTRACT

It is well known that, many kinds of industrial organic waste can be used for biogas production, but the biogas and methane yields depend on the biodegrability of the compounds in raw material. Recent studies are aimed to increase the biodegradability of organic matter by many pretreatment processes. In this study, belt-filter press sludge which has been taken from the waste water treatment plant of ETAP, has been used in experiments, basic and/or microwave radiation (MW) pretreatments have been carried out in order to determine water solubility and biogas yield. The aqueous sludge slurry ( 13,17 % solid by mass) have been treated with NaOH (5 %, 10 %, 15 % by mass of the solid) and without chemicals, at room temperature and/or pretreatment with MW radiation having 700 W for 5, 10 and 15 min.under reflux. The percentage of water solubility of sludge were determined gravimetrically by filtering the aqueous mixtures with glass wool and then drying and weighing the solid. The filtrates obtained from the pretreatments that result high yield of watersoluble compounds were used in anaerobic processes to determine the biogas yield. The filtrates were used for anaerobic digestion at 303 K, at pH’s 7 and for 35 days. While the anaerobic process proceeds, the volumes of gas, produced, were measured at every three-day intervals. The volume of biogas, which was collected at usually three-day intervals, was measured and calculated at STP (standart temperature and pressure). It was found that the maximum water solubility, the amount of maximum biogas and methane content of biogas were 48,17 % (by mass), 147,82 mL, 77,50 mL and 54,59 % (by volume), respectively. It was conculuded that the sludge is used for biogas production efficiently after pretreament for converting into water soluble substances.

Keywords : Belt press sludge, water solubility, biogas, basic pretreatment, microwave radiation