Effects of pH on Phosphorus Recovery from Different Composition of Food Waste Using Anaerobic Batch Digestion

Anaerobic digestion is a process by which microorganisms break down biodegradable material in the absence of oxygen. The process involves hydrolysis, acidogenesis and methanogenesis stages. Anaerobic digestion of food waste has been widely investigated for biogas recovery but limited study was performed on phosphorus recovery, which is reported depleting. Food waste is produced every day and dumped on landfill for final disposal which may lead to environmental issues such as odour problems and greenhouse gases release, due to decomposing of food waste, hence impacts global climate change. In anaerobic digestion pH is a very crucial parameter in an attempt to recover phosphorus as it highly influences the production of organic acids during acidogenesis

Effects of substrate to inoculum ratio on Phosphorus Recovery from Different Composition of Food Waste using Anaerobic Batch Digestion

Anaerobic digestion is a process by which microorganisms break down biodegradable material in the absence of oxygen. The process involves hydrolysis, acidogenesis, acedogenesis and methanogenesis stages. Anaerobic digestion of food waste has been widely investigated for biogas recovery but limited study was performed on phosphorus recovery. Substrate to inoculum ratio is a very crucial parameter in anaerobic digestion in an attempt to recover phosphorus as it highly influences the production of organic acids during acidogenesis. Therefore, this study was carried out to investigate phosphorus recovery at different ratio of substrate to inoculum, where substrates was fixed to ratio 1.0 while inoculum ratio varied to 1.5, 2.0, 2.5, 3.0, 3.5 throughout the digestion process. The main substrate used in the anaerobic digestion was food waste which was segregated into different composition namely carbohydrates rich-food waste, fiber rich-food waste and protein rich-food waste. The phosphorus recovery was performed using anaerobic batch digester at mesophilic (35±1oC) condition and pH= 6.0 for 15 days. Semi treated palm oil mill effluent (POME) was used as the inoculum to boost up the anaerobic digestion. The results indicate that substrate to inoculum ratio (1.0 : 2.0) was the optimum ratio to recover phosphorus, where protein rich-food waste shows the phosphorus recovery was about 40.8%, followed by carbohydrate rich-food waste and fibre rich-food waste with 32.8% and 26.2%, respectively. This study is very important in resources recovery from wastes as it provides information on a new strategies for phosphorus recovery from food wast

Landslide Susceptibility in Relation to Correlation of Groundwater Development and Ground Condition

Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of groundwater rise on slope stability. Thus, this study is intended to focus on the rise of the groundwater level from the bottom of the slope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors (i.e., infiltration and surface runoff). Saturated sand was used for slope modeling, and sand densities of 1523 kg/m3, 1562 kg/m3, and 1592 kg/m3 were tested with a constant slope angle of 45°. Another set of experiments was also performed on slopes having angles of 25°, 45°, and 60° and with a maintained density of sand at 1562 kg/m3. Through observation, failure was initiated first at the toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included in SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the lowest slope angle. However, faster occurrence of collapse in denser soil was identified and could be contributed by the faster pore water pressure development

Anaerobic digestion of screenings for biogas recovery

Screenings comprise untreatable solid materials that have found their way into the sewer. They are removed during preliminary treatment at the inlet work of any wastewater treatment process using a unit operation termed as a screen and at present are disposed of to landfill. These materials, if not removed, will damage mechanical equipment due to its heterogeneity and reduce overall treatment process, reliability and effectiveness. That is why this material is retained and prevented from entering the treatment system before finally being disposed of. The amount of biodegradable organic matter in screenings often exceeds the upper limit and emits a significant amount of greenhouse gases during biodegradation on landfill. Nutrient release can cause a serious problem of eutrophication phenomena in receiving waters and a deterioration of water quality. Disposal of screenings on landfill also can cause odour problem due to putrescible nature of some of the solid material. In view of the high organic content of screenings, anaerobic digestion method may not only offer the potential for energy recovery but also nutrient. In this study, the anaerobic digestion was performed for 30,days, at controlled pH and temperature, using different dry solids concentrations of screenings to study the potential of biogas recovery in the form of methane. It was found screenings have physical characteristics of 30% total solids and 93% volatile solids, suggesting screenings are a type of waste with high dry solids and organic contents. Consistent pH around pH 6.22 indicates anaerobic digestion of screenings needs minimum pH correction. The biomethane potential tests demonstrated screenings were amenable to anaerobic digestion with methane yield of 355,m3/kg VS, which is comparable to the previous results. This study shows that anaerobic digestion is not only beneficial for waste treatment but also to turn waste into useful resources

Comparison of phosphorus recovery from different organic substrates using Simple Batch Mesophilic Reactor (SBMR)

Anaerobic digestion is a technology that widely applied for treatment of organic wastes that are easily biodegrable in nature. This few decades, this technique has become the centre of attention in resource recovery field of research, as it widely used in converting waste into resources, such as biogas and nutrient. While the use of anaerbic digestion for biogas recovery has been extensively studied, phosphorus recovery using anaerobic digestion isstill under utilised. Therefore, this study was carried out to investigate the anaerobic digestion of different organic substrates, namely food waste, palm oil mill effluent sludge and water treatment sludge in recovering phosphorus using a simple batch mesophilic reactor. Three reactors containing different substrates with working volume of 400 mL were set up to perform anaerobic digestion at optimum conditions (35oC, pH6.0 and 80 rpm) for 30 days. The results show that the highest phosphorus was from palm oil mill effluent sludge, followed by food waste and water treatment sludge with 57.88%, 31.94% and 26.47%, respectively

Landslide Susceptibility in Relation to Correlation of Groundwater Development and Ground Condition

Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of groundwater rise on slope stability. *us, this study is intended to focus on the rise of the groundwater level from the bottom of the slope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors (i.e., in2ltration and surface runo3). Saturated sand was used for slope modeling, and sand densities of 1523 kg/m3 , 1562 kg/m3 , and 1592 kg/m3 were tested with a constant slope angle of 45°. Another set of experiments was also performed on slopes having angles of 25°, 45°, and 60° and with a maintained density of sand at 1562 kg/m3 . *rough observation, failure was initiated 2rst at the toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included in SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the lowest slope angle. However, faster occurrence of collapse in denser soil was identi2ed and could be contributed by the faster pore water pressure development