Compost

Produced water (PW) is the main waste stream generated from oil and gas extraction. Nowadays, half of the global PW volume is managed through environmentally controversial and expensive disposal practices, such as re-injection through deep wells. In dry areas such as in the Arabian Peninsula, PW could be reused to irrigate crops, creating environmental, economic and social value. However, the quality of most PWs remains challenging as their high salinity, sodicity and alkalinity can degrade soil fertility and crop yield.
Agroecosystems make up a significant portion of terrestrial ecosystems and receive a disproportionally high amount of terrestrial nitrogen inputs from fertilizer, leading to nitrogen loss and associated environmental problems. Integrated crop livestock systems, such as pasture-integrated crop rotations, may be more environmentally sustainable however the long-term effects of this management practice on soil microorganisms and nitrogen transformations are not well understood.
Soil contamination by potentially toxic elements (PTEs) has led to adverse environmental impacts. In this review, we discussed remediation of PTEs contaminated soils through immobilization techniques using different soil amendments with respect to type of element, soil, and amendment, immobilization efficiency, underlying mechanisms, and field applicability. Soil amendments such as manure, compost, biochar, clay minerals, phosphate compounds, coal fly ash, and liming materials are widely used as immobilizing agents for PTEs.