Greywater irrigation as a source of organic micro-pollutants to shallow groundwater and nearby surface water

Increased water demands due to population growth and increased urbanisation have driven adoption of various water reuse practices. The irrigation of greywater (water from all household uses, except toilets) has been proposed as one potential sustainable practice. Research has clearly identified environmental harm from the presence of micro-pollutants in soils, groundwater and surface water. Greywater contains a range of micro pollutants yet very little is known about their potential environmental fate when greywater is irrigated to soil. Therefore, this study assessed whether organic micro-pollutants in irrigated greywater were transferred to shallow groundwater and an adjacent surface waterway. A total of 22 organic micro-pollutants were detected in greywater. Six of these (acesulfame, caffeine, DEET, paracetamol, salicylic acid and triclosan) were selected as potential tracers of greywater contamination. Three of these chemicals (acesulfame, caffeine, DEET) were detected in the groundwater, while salicylic acid was also detected in adjacent surface water. Caffeine and DEET in surface water were directly attributable to greywater irrigation. Thus the practice of greywater irrigation can act as a source of organic micro-pollutants to shallow groundwater and nearby surface water. The full list of micro-pollutants that could be introduced via greywater and the risk they pose to aquatic ecosystems is not yet known

Formic acid synthesis using CO₂ as raw material: Techno-economic and environmental evaluation and market potential

The future of carbon dioxide utilisation (CDU) processes, depend on (i) the future demand of synthesised products with CO₂, (ii) the availability of captured and anthropogenic CO₂, (iii) the overall CO₂ not emitted because of the use of the CDU process, and (iv) the economics of the plant. The current work analyses the mentioned statements through different technological, economic and environmental key performance indicators to produce formic acid from CO₂, along with their potential use and penetration in the European context. Formic acid is a well-known chemical that has potential as hydrogen carrier and as fuel for fuel cells. This work utilises process flow modelling, with simulations developed in CHEMCAD, to obtain the energy and mass balances, and the purchase equipment cost of the formic acid plant. Through a financial analysis, with the net present value as selected metric, the price of the tonne of formic acid and of CO₂ are varied to make the CDU project financially feasible. According to our research, the process saves CO₂ emissions when compared to its corresponding conventional process, under specific conditions. The success or effectiveness of the CDU process will also depend on other technologies and/or developments, like the availability of renewable electricity and steam