Investigation of the energy (biogas) production from co-digestion of organic waste materials

Abstract

Biogas production rate was investigated from the co-digestion of 39 kg each of food waste, cow dung and water; 39 kg each of food waste, poultry droppings and water as well as 39 kg each of food waste, fruit waste and water in 43 litres plastic digester setup. Although organic waste mix ratios with higher moisture content can influence decomposition rate, HRT and biogas yield, 1:1:1 mix ratio was used in this investigation. The total rate of biogas produced from the codigestion of food waste with poultry droppings and water (39 kg) in the ratio of 1:1:1 was 4120 g of raw biogas and 3700 g of purified biogas within with Hydraulic Retention Time 32 days, whereas, the co-digestion of food waste with cow dung and water (39 kg) in the same 1:1:1 ratio yielded a total raw biogas of 5830 g and 4920 g of purified biogas with HRT of 35 days. However, co-digestion of food waste with fruit waster and water (39 kg) in the same ratio yielded a total raw biogas of 5010 g and purified biogas 4330 g with HRT of 33 days. Raw biogas produced from each organic feedstock was channelled through a scrubbing unit comprising distilled water and Type B silica gel. After the raw biogas had passed through the distilled water stream, its pH dropped drastically from neutral range to ultra-acidic range (7-3.2), while it also had milky color and sour taste, indicating the presence of carbonic acid (H2CO3) as a result of carbon dioxide (content in the raw biogas) dissolution in the distilled water. Color of the Type B silica gel changed from crystal pink to crystal blue, indicating the absorption of water content in the biogas by silica gel particles. Organic waste is a renewable energy resource that can offset Nigeria's increasing demand for energy if harnessed and processed into cooking gas and organic fertilizers before disposal, in which case can also prevent Green House Gas (GHG) emissions into the atmosphere.

Modelling and simulation of high density polyethylene liner installation in engineered landfill for optimum performance

“…An engineered landfill system also known as sanitary landfill is a waste containment facility that involves carefully engineered excavation of the ground and burying/compaction of waste materials in layers to protect the environment against the effects of landfill gas and leachate from decomposing organic waste (Ikpe et al, 2018;Orhorhoro et al, 2018). Leachate which contains organic and inorganic chemicals, acidic oxides such as SO2 and NOx, heavy metals as well as pathogens is a toxic liquid product from decomposing organic waste (Ikpe et al, 2019a;Rowe and Yu, 2013).…”

Half-metallic ferromagnetism; Spin-polarization; Band structure; Density of state

“…This practice leads to environmental dilapidation as well as the formation of leachate, a black liquid containing organic and inorganic chemicals, heavy metals as well as pathogens, which can pollute groundwater and surface water causing public health risks. Exposure of humans to leachate contaminated waters can lead to diseases like diarrhoea, cholera, skin diseases, respiratory allergies, malaria, tuberculosis, jaundice cancer from the pathogens in the leachate and Lassa fever which is reported to be caused by a vector known as mastomys natalensis (Ikpe et al, 2018). There is a high risk of contamination and spread of most of the diseases as they are communicable through humans and animals such as rats, flies, birds and even humans who find refuge in open dumpsites, becoming a source for spreading such communicable diseases .…”