Biochar as a novel technology for treatment of onsite domestic wastewater: A critical review

Abstract

Globally, about 2.7 billion people depend on onsite sanitation systems (OSS) (e.g., septic tanks) for their sanitation needs. Although onsite sanitation systems help in providing primary treatment for domestic wastewater, they don’t effectively remove nutrients, pathogens, and other inorganic contaminants. Previous studies have posited that the use of post treatment systems which incorporate biochar leads to improved contaminant removal efficiency. However, the mechanism through which contaminants are removed and factors potentially affecting the removal are still understudied. To fill this knowledge gaps, this review discusses factors which affect efficiency of biochar in removing contaminants found in onsite domestic wastewater, modifications applied to improve the efficiency of biochar in removing contaminants, mechanisms through which different contaminants are removed and constraints in the use of biochar for onsite wastewater treatment. It was noted that the removal of contaminants involves a combination of mechanisms which include adsorption, filtration, biodegradation, ion exchange, pore entrapment. The combination of these mechanisms is brought about by the synergy between the properties of biochar and microbes trapped in the biofilm on the surface of the biochar. Future areas of research such as the modification of biochar, use of biochar in the removal of antibiotic resistant genes (ARGs), application of wet carbonization methods and resistance of biochar to physical disintegration are also discussed. This study provides useful information that can be applied in the use of biochar for the treatment of wastewater and guide future design of treatment systems for optimized treatment performance.

A Review on Biochar as an Adsorbent for Pb(II) Removal from Water

“…Increasing the temperature during pyrolysis leads to an increase in the specific surface area [80]. This happens when the volatile matters present in the feedstock starts escaping the pores as the temperature increases and, therefore, the surface area increases [81]. However, a non-woody biomass appeared to have high nutrient and ash contents, which volatized and increased the surface area and porosity of biochar under a high pyrolysis temperature [57].…”

Biological Wastewater Treatment

“…Bioremediation methods like aerobic treatment and anaerobic digestion reduce environmental impact by promoting organic breakdown [35]. Bioremediation removes pollutants from onsite municipal wastewater using biochar through several processes [35,36].…”

“…Figure 3.Bioremediation removes pollutants from onsite municipal wastewater using biochar through several processes[35,36].…”

Properties and Possibilities of Using Biochar Composites Made on the Basis of Biomass and Waste Residues Ferryferrohydrosol Sorbent

“…Transforming waste into products with added value is consistent with the assumptions of the circular economy. Due to its specific properties, biochar can be used in many different environmental processes, related, among others, to the removal of pollutants from water, soil or gases [ 14 , 16 , 17 , 18 , 19 ]. As indicated by [ 20 ], such features of biochar, including large specific surface area, porous structure, a large number of surface functional groups (including carboxyl, hydroxyl and phenolic), mineral components and hydrophobicity [ 16 ], determine its use as an adsorbent for removing contaminants from aqueous solutions.…”