Biochar carrier application for nitrogen removal of domestic WWTPs in winter: challenges and opportunities

Abstract

Biofilm processes have a better nitrogen removal ability than traditional activated sludge at low temperatures (< 15 °C). Many biofilm processes, as well as integrated biofilm and activated sludge processes, are potential and realizable nitrogen removal upgrading methods for domestic wastewater treatment plants (WWTPs). Therefore, biofilm packing material is attractive for domestic WWTP upgrading and reconstruction in winter. For a half decade, researchers have successfully applied activated carbon to biochar as biofilm carrier in the wastewater treatment field. Biochar, as a biostable soil amendment with pores and crevices on its surface, has been applied in the soil-plant system, which promoted the adsorption of NH and NO, decreased NO emission, transcriptional level of narG, nxrA, and nirS, and changed the microbial community composition for better nitrogen removal. However, in the field of wastewater treatment, the study of biochar-packed process is merely in the laboratory stage of simulated wastewater, which deserves further research in the future. In this mini review, we will discuss the performances of different processes at low temperatures, the related mechanism of the biochar-packed process for nitrogen removal, and other potential applications of biochar carriers.

Biochar application in biofiltration systems to remove nutrients, pathogens, and pharmaceutical and personal care products from wastewater

“…A limited number of studies have explored biochar application in wastewater treatment process for N removal (He, Ding, Wang, et al., 2018). In this review, we mainly focus on soil‐based biofiltration systems with similar configurations (trickling filter, CW, and SWIS) that have incorporated biochar for N removal from on‐site wastewater (Table 1).…”

“…At low temperatures, biochar‐amended CWs also showed better performance compared with the conventional wetland (He et al., 2018b; He, Ding, Wang, et al., 2018). For example, during winter (4.9 °C), CWs with 10 and 20% (v/v) biochar amendment achieved 85.7 ± 6.2 and 91.7 ± 3.8% TN removal, which was statistically significantly higher than the conventional CW (73.6 ± 9.6%); this result was possibly due to the labile organic C released from biochar for denitrification (J. Li et al., 2019).…”

Enhanced landfill leachate treatment in sequencing batch biofilm reactors (SBBRs) amended with zeolite and biochar

“…Biochar both adsorbs recalcitrant organic matter and provides an attachment surface for microbial biofilms. 26,33 The adsorbed recalcitrant organic matter may be slowly degraded to simple organic molecules by hydrolytic bacteria and then consumed by either denitrifiers in the anoxic stage or aerobic heterotrophs in aerobic stage, thus regenerating the active adsorption sites on the biochar surface. Prior studies showed that activated carbon can be bioregenerated in situ by organic matter degradation and desorption.…”

“…In addition, prior studies also showed that biochar can provide an attachment surface for biofilm growth in wastewater treatment systems. 26,27 Both zeolite and biochar are promising materials for enhancing biological treatment of domestic wastewater, yet studies of the combined use of these materials for landfill leachate treatment have not been carried out previously. Hence, the overall goal of this study was to enhance N, COD and color removal from landfill leachate in SBBRs amended with zeolite and biochar.…”

A Life Cycle Assessment of the Combined Utilization of Biomass Waste-Derived Hydrochar as a Carbon Source and Soil Remediation

“…Recently, studies have shown that dissolved organic matter (DOM) discharged from biochar prepared from almond, walnut shell, wheat straw, and so on could be a carbon source available to organisms, thus improving denitrification efficiency. − Hydrochar can affect the range and activity of microorganisms in wastewater treatment plants (WWTPs), thereby enhancing denitrification. After biological treatment in WWTPs, the spent hydrochar can be further used in soil remediation. ,− However, these studies are individual in nature and are usually limited to one application of hydrochar, resulting in the waste of resources. It is not known how well hydrochar can be applied to a wastewater treatment and soil conditioning system if the two applications are combined in a series.…”