Biosolids towards Back-To-Earth alternative concept (BEA) for environmental sustainability: a review.

Biosolids are a nutrient-rich stable substance obtained during wastewater treatment process. With amplifying population and industrial development, upsurge of biosolid generation is also speculated. Biosolids are endowed with essential plant nutrient (macro- and micro-nutrients) which qualifies them to be used as soil amendment and in turn dwindles the use of chemical fertilizers. The characteristics of biosolid depends on the nature of the treatment process. In this regard, it would be possible to recycle certain nutrients from the agricultural use of biosolids and could be a sustainable solution to the management of this waste. Biosolids may therefore serve as a key tool for farm utilization. It improves the soil health through nutrient supply and promotes the plant growth. Furthermore, they are slow-release fertilizer and hence, restrains from groundwater contamination. This review, in a nutshell, unravels the influence of biosolids on land application, its effect on soil properties, agricultural and horticultural crops, environmental ramification of biosolids in restoring the degraded land and carbon sequestration.

Application of sludge-derived KOH-activated hydrochar in the adsorptive removal of orthophosphate.

Hydrochar, a hydrothermally carbonized product, has gained attention recently as an adsorbent, among its wide environmental applications. In this study, sludge from the paper recycling industry, having a lower pollution load, was used to produce hydrochar, followed by pre-activation and post-activation using KOH. Characterizations were performed for structural morphology (SEM and TEM), molecular functionalities (FTIR) and textural features (BET surface area). Furthermore, Response Surface Methodology (RSM) was used to optimize the adsorption parameters for the removal of orthophosphate with different hydrochars. This study aimed at a low-cost, waste-to-wealth, and negative emission technology for simultaneous solid waste management and orthophosphate removal in aqueous solution. It was predicted from the adsorption experiment that an orthophosphate dose of 100 mg L-1 at substrate pH 5.11 will result in the adsorption of 9.59 mg orthophosphate per g of post-activated hydrochar after 28.6 h, which was validated using further confirmation study.