Influence of Substrate to Biomass Ratio (F /M) and pH On Microbial Stability of Activated Sludge

• Main Author: Mohd Said, Muhammad Afif
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2012
• Subjects: TP Chemical technology
• Online Access: http://utpedia.utp.edu.my/8932/1/2011-Influence%20Of%20Subtrate%20To%20Biomass%20Ratio%20%28F_M%29%20And%20PH%20On%20Microbial%20Stability%20Of%20Activated%20Slud.pdf; http://utpedia.utp.edu.my/8932/
• Institution: Universiti Teknologi Petronas

Activated sludge contains biological floes composed of bacteria that degrade the organic matter in the waste water for its growth. The microbial stability of the activated sludge represented by the characteristics of the floes. Project is focused on activated sludge used by most operating wastewater treatment plant owned by PETRONAS. Bacteria chosen will be BIOCHEM (BCI-103) brand. The bacteria are taken from a gas processing plant located in Kerteh, Terengganu. The main objective of this project to study on the influence of two major parameters in wastewater, which are the substrate to biomass ratio or also known as food to microorganism (FIM) and pH, to the characteristics of the bacteria floes. Optimum value of F/M and pH obtained from this project will be recommended to further enhance the wastewater process control at the processing plant. Besides that, the characteristics of floes that obtained at different F 1M and pH can be served as informative data to further enhance the understanding of the bacteria used. Nowadays, with the increasing industrial activity, usage of hazardous chemicals escalates thus endangering the environment. News raised on the environment pollution especially the water pollution effecting the seas and rivers. One of the main causes of this pollution is the ineffective operation of wastewater treatment plant. Many microbially-related activated sludge solids separation problems occurred such as dispersed growth, filamentous bulking and foam formation. Existing design parameter such as sludge age, Chemical Oxygen Demand (COD), and Sludge Volume Index (SVI) can't predict the stability of the bacteria floes. These design parameters are more oriented to the final goal of releasing effluent below the standard limit set by the government. Thus, the project will focus on the study of F/M and pH as design parameters and their influence to the bacteria floes. The scope of study for this project contains three elements which are the F 1M, pH, and the microbial stability of the activated sludge. With others parameters such as temperature, Mixed Liquor Suspended Solids (MLSS), and sludge retention time (SRT) set constant, F/M and pH are manipulated to obtained the results. Microbial stability of activated sludge is judged by the characteristics of bacteria floes. Activated sludge is stable when microorganisms to stick to each other and to nonbiological particles as sludge floes (Jenkins et al.,2004). Increase size of floc diameter indicates the sludge is stable and at optimum condition. Activated sludge is populated by all kinds ofbacterias. However, to study the microbial stability for this experiment, six species were chosen which are amoebae, flagellates, free swim ciliates, crawling ciliates, stalked ciliates, and rotifer. The abundance of these species are found and analyzed as each species has its own function and indication for the condition of sludge. Research starts by searching for any other relevant journal or article published by othf;lr researches and from there, the results would be review and useful information will be summarize and taken as an information to this research. Next, contacts are made with the industry personnel in order to obtain the sample bacteria and knowledge of the activated sludge system used in the plant. Then, research progress experimentally in the laboratory and the results gained are discussed and documented. Findings from this project show that the microbial stability of activated sludge is influenced by F 1M and pH. Under different F 1M and pH conditions, bacteria floes particles and sizes are different. Under microscope, bacteria population is analyzed and documented. Efficiency which is calculated by the removing percentage of the (COD) is plotted. Further findings are discussed in latter part of this dissertation.