افزايش توليد بيوگاز از لجن مازاد تصفيه خانه ي شهري با روش هاي مختلف پيش فراوري دما پايين

چكيده انگليسي :

Enhancement of Biogas Production from Waste Activated Sludge using Different Low Temperature Pretreatment Methods Mehdi Rafiee m rafiee@ce iut ac ir January 15 2014 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Hamid Zilouei hzilouei@cc iut ac ir Ahmad Asadinezhad asadinezhad@cc iut ac ir Abstract Excess sludge from municipal wastewater treatment plants WWTP take approximately up to 60 of total cost of plant in order to management dewatering transport and disposal Anaerobic digestion present in most of WWTP is usually used for stabilization of sludge before disposal Considerable research has been conducted to enhance the proficiency accelerating conversion process and reducing the excess sludge volume in processes of producing biogas as a renewable energy source from urban wastewater treatment plant sludge Excess sludge from wastewater treatment plant which is an environmental pollutant contains high quantity of organic compounds COD about 60000 mg L for producing biogas Excess sludge of urban wastewater treatment plant contains high quantity of microbial cells with rigid wall which prevents microorganisms from reaching the organic containments inside the cells which in turn reduces the biogas production efficiency and elongates the anaerobic fermentation Various biological chemical and physical procedures have been used for breaking these cells and to accelerate this stage of fermentation In this project two types of feed including secondary sludge and mixed sludge a mixture of initial and secondary sludge were used In first set of experiments basic ultrasonic and microwave pretreatment at ambient temperature 20 C and 40 C were done in case of mixed sludge to enhance the biogas production and reduce the excess sludge volume In second set of experiments chemical pretreatment with H2O2 and basic pretreatment with NaOH and KOH as well as acidic pretreatment with HCl were used on secondary sludge at ambient temperature 20 C First set of experiment in which a comparison between basic microwave and ultrasonic pretreatment of mixed sludge at ambient and medium temperature was performed showed that the highest efficiency belongs to the basic pretreatment pH 12 and 20 C and 365 mL biogas gr COD was obtained which shows a 242 increase in comparison with untreated sample After that the highest efficiency belonged to the sample at condition of 40 C and pH 12 and obtained result equals to 352 mL biogas gr COD Increase of methane containment in produced biogas from 50 obtained from raw sludge to the 72 from ultrasonic pretreated sample at 20 C shows the biogas quality development In case of the second set of experiment on the secondary sludge a comparison between different chemical pretreatment methods at ambient temperature 20 C was performed and the highest biogas production enhancement in comparison with untreated sample belonged to the sample which was pretreated by KOH and it was 72 After that the sample pretreated by H2O2 at concentration of 2400 mg H2O2 L with 69 efficiency had the highest efficiency The highest rate of methane containment increase in biogas was obtained through the sample pretreated by H2O2 at concentration of 2400 mg H2O2 L and it was 64 Key words Biogas anaerobic digestion excess sludge microbial cells pretreatment

رفيعي، مهدي

افزايش توليد بيوگاز از لجن مازاد تصفيه خانه ي شهري با روش هاي مختلف پيش فراوري دما پايين

هضم بي هوازي , سلول هاي ميكروبي , پيش فراوري قليايي