Techno-economic analysis of electricity generation from household sewage sludge in different regions of Nigeria

Waste management has been a chronic environmental challenge in Nigeria, coupled with declining economic performance due to energy crises. This study was designed to estimate electricity potential of sewage sludge to meet the 2030 Renewable Energy target. However, there was a need to fill the gap in data related to wastewater management in Nigeria. The wastewater and sludge generated from households were evaluated based on data on population, access to water, and coverage of sewer networks. Consequently, the technical and economic feasibility of electricity generation was assessed using Anaerobic Digestion (AD)1 and Incineration (INC)2 scenarios. The core results found that North Central had the highest potential for wastewater generation (142.8-403.6 billion litres/yr) and collection (8.3-37.5 billion litres/yr) over 20 years. However, the South East had the highest average sewer collection rate of 9.08 %. The AD technology was the most technically viable, with a maximum generation of 6.8 GWh/yr in the North Central. In comparison, the INC outperformed AD in most of the financial viability indicators considered viz-a-viz: Life Cycle Cost (LCC),3 Net Present Value (NPV),4 Pay Back Period (PBP),5 Internal Rate of Return (IRR),6 Levelized Cost of Energy (LCOE).7 The AD had a higher NPV of 16.3-69.58 million USD and a shorter PBP of about 4 years. The INC had a lower LCC of 0.1-0.34 million USD, LCOE of 0.046-0.094 USD/kWh, and a higher IRR of 19.3-25 %. Additionally, the sensitivity of NPV and INC to changes in economic factors would be noteworthy for investors and policymakers. Ultimately, the choice of technology should reflect the fiscal goal and priorities of a project.

Health risk assessment for uptake and accumulation of pharmaceuticals in jute mallow (Corchorus olitorius) irrigated with treated hospital wastewater

The use of reclaimed water for crop irrigation presents a route through which pharmaceuticals enter the agro-environment, raising concerns about their potential inclusion into the food chain and associated health risks. The main objective of this study was to determine the accumulation of six pharmaceuticals (paracetamol, diclofenac and ibuprofen, ciprofloxacin, tetracycline, and sulfamethoxazole) in edible part of jute mallow (JM) (Corchorus olitorius) irrigated with treated hospital wastewater (THWW) and potential health risks associated with the consumption of the contaminated JM. In a greenhouse experiment, JM vegetable was grown in soils irrigated with groundwater and THWW. After 4 weeks of cultivation, the pharmaceutical concentrations in the soil and JM tissues were determined. The uptake and accumulation of the pharmaceuticals in the irrigated JM and the human health risks associated with their consumption were evaluated. Results showed that the THWW-irrigated and groundwater-irrigated soils accumulated all the studied pharmaceuticals except paracetamol and sulfamethoxazole, with the concentrations in the soil before and after irrigation ranging from 0.01 to 0.14 μg g-1 and 0.03 to 1.35 μg g-1, respectively. In JM leaves, the accumulation was in the order of tetracycline > ciprofloxacin > ibuprofen > diclofenac and tetracycline > ciprofloxacin > diclofenac > ibuprofen under THWW-irrigated and groundwater-irrigated treatments, respectively. Under both treatments, the uptake and accumulation of the studied pharmaceuticals were in the order of roots > stem > leaves. The health risk assessment indicated that the consumption of the studied pharmaceuticals through JM implies some risks to human health and the risks were in the order of tetracycline > diclofenac > ciprofloxacin > ibuprofen > paracetamol > sulfamethoxazole. This study has demonstrated that irrigation with reclaimed water is a major route of pharmaceuticals into the food chain and a key determinant of associated health risks.