Municipal sludge minimization: evaluation of ultrasonic and acidic pretreatment methods and their subsequent effects on anaerobic digestion

Download

index.pdf

Date

2009

Author

Apul, Onur Güven

Metadata

Show full item record

Item Usage Stats

192
views

507
downloads

Sludge management is one of the most difficult and expensive problems in wastewater treatment plant operation. Consequently, ‘sludge minimization’ concept arose to solve the excess sludge production by sludge pretreatment. Sludge pretreatment converts the waste sludge into a more bioavailable substrate for anaerobic digestion and leads to an enhanced degradation. The enhanced degradation results in more organic reduction and more biogas production. Therefore, sludge pretreatment is a means of improving sludge management in a treatment plant. Among pretreatment methods, acidic pretreatment has been subject of limited successful studies reported in the literature. On the contrary; ultrasonic pretreatment was reported as an effective pretreatment method. Main objective of this study was to investigate the effects of these two pretreatment methods and their combination in order to achieve a synergistic effect and improve the success of both pretreatment methods. Experimental investigation of pretreatment methods consists of preliminary studies for deciding the most appropriate pretreatment method. Anaerobic batch tests were conducted for optimization of the parameters of selected method. Finally, operation of semi-continuous anaerobic reactors was to investigate the effect of pretreatment on anaerobic digestion in details. Preliminary studies indicated that, more effective pretreatment method in terms of solubilization of organics is ultrasonic pretreatment. Fifteen minutes of sonication enhanced 50 mg/L initial soluble COD concentration up to a value of 2500 mg/L. Biochemical methane potential tests indicated that the increased soluble substrate improved anaerobic biodegradability concurrently. Finally, semi-continuous anaerobic reactors were used to investigate the efficiency of pretreatment under different operating conditions. Results indicate that at SRT 15 days and OLR 0.5 kg/m3d ultrasonic pretreatment improved the daily biogas production of anaerobic digester by 49% and methane percentage by 16% and 24% more volatile solids were removed after pretreatment. Moreover, even after pushing reactors into worse operating conditions such as shorter solids retention time (7.5 days) and low strength influent, pretreatment worked efficiently and improved the anaerobic digestion. Finally cost calculations were performed. Considering the gatherings from enhancement of biogas amount, higher methane percentage and smaller amounts of volatile solid disposal from a treatment plant; installation and operation costs of ultrasound were calculated. The payback period of the installation was found to be 4.7 years.

Subject Keywords

Environmental engineering.

URI

http://etd.lib.metu.edu.tr/upload/12610366/index.pdf
https://hdl.handle.net/11511/18410

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Combination of alkaline solubilization with microwave digestion as a sludge disintegration method: effect on gas production and quantity and dewaterability of anaerobically digested sludge Doğan, Ilgın; Sanin, Faika Dilek; Department of Environmental Engineering (2008) The significant increase in the sewage sludge production in treatment plants makes anaerobic digestion more important as a stabilization process. However hydrolysis is the rate-limiting step of anaerobic digestion because of the semirigid structure of the microbial cells. Pretreatment of waste activated sludge (WAS) leads to disruption of cell walls and release of extracellular and intracellular materials. Therefore biodegradability of sludge will be improved in terms of more biogas production and sludge mi...
Development of a fuzzy rule based remedial priority ranking system for contaminated sites Polat, Şener; Ünlü, Kahraman; Department of Environmental Engineering (2009) Evaluation of contaminated sites based on human health and environmental hazards is an essential task for the proper management of the contaminated sites. A large number of contaminated sites have been waiting for remediation all over the World. However, contaminated site remediation is generally a difficult, time consuming and very expensive process. Ranking systems for contaminated sites are useful tools to determine the remedial priority and to manage the available remediation budget in the most efficien...
Modeling the water quality in Ulubat Lake Yenilmez, Firdes; Aksoy, Ayşegül; Department of Environmental Engineering (2007) Lakes can be used for recreational purposes, agricultural irrigation, domestic water supply or industrial use. However, these functions of the lakes can be impaired due to excess nutrient loadings from industrial facilities, agricultural activities, and discharge of wastewaters from sewage systems. Uluabat Lake is one of the important lakes in Turkey faced with water quality problems due to excess nutrient loading from point and non-point sources. In this study, Water Quality Analysis Simulation Program (WA...
Experimental Study on Maize Cob Trickling Filter-Based Wastewater Treatment System: Design, Development, and Performance Evaluation Ali, Imran; Khan, Zahid M.; Sultan, Muhammad; Mahmood, Muhammad H.; Farid, Hafiz U.; Ali, Mohsin; Nasir, Abdul (HARD Publishing Company, 2016-01-01) In developing countries, good-quality water is contaminated due to the disposal of untreated municipal and industrial wastewater (WW) into natural water reservoirs. Most of the wastewater is not treated properly according to international standards, and usually is disposed of and/or utilized for irrigation without appropriate treatment. The main hurdles in providing wastewater treatment (WWT) in developing countries include high costs, and the poor design, installation, and operation of conventional WWT sys...
Modeling natural attenuation of petroleum hydrocarbons (btex) in heterogeneous aquifers Uçankuş, Tuğba; Ünlü, Kahraman; Department of Environmental Engineering (2005) Natural Attenuation can be an effective cleanup option for remediation of Groundwater contamination by BTEX. One of the important aspects of the methodology that has been recognized recently is that mass removal rates, the most important parameters used to determine effectiveness of the methodology, is controlled by groundwater flow regime, which to a large extent controlled by aquifer heterogeneity. Considering this recognition, the primary objective of this research is to quantitatively describe the relat...

Citation Formats

O. G. Apul, “Municipal sludge minimization: evaluation of ultrasonic and acidic pretreatment methods and their subsequent effects on anaerobic digestion,” M.S. - Master of Science, Middle East Technical University, 2009.