Efficient Adsorption Removal of Phosphate from Rural Domestic Sewage by Waste Eggshell-Modified Peanut Shell Biochar Adsorbent Materials

Abstract

In order to promote the improvement of the rural living environment, the treatment of rural domestic sewage has attracted much attention in China. Meanwhile, the rural regions’ sewage discharge standards are becoming increasingly stringent. However, the standard compliance rate of total phosphorus (TP) is very low, and TP has become the main limiting pollutant for the water pollutants discharge standards of rural domestic sewage treatment facilities. In this study, waste eggshell (E) was employed as a calcium source, and waste peanut shell (C) was employed as a carbon source to prepare calcium-modified biochar adsorbent materials (E-C). The resulting E-C adsorbent materials demonstrated efficient phosphate (P) adsorption from aqueous solutions over the initial pH range of 6–9 and had adsorption selectivity. At an eggshell and peanut shell mass ratio of 1:1 and a pyrolysis temperature of 800 °C, the experimental maximum adsorption capacity was 191.1 mg/g. The pseudo second-order model and Langmuir model were best at describing the adsorption process. The dominant sorption mechanism for P is that Ca(OH)2 is loaded on biochar with P to form Ca5(PO4)3OH precipitate. E-C was found to be very effective for the treatment of rural domestic sewage. The removal rate of TP in rural domestic sewage was 91–95.9%. After adsorption treatment, the discharge of TP in rural sewage met the second-grade (TP < 3 mg/L) and even first-grade (TP < 2 mg/L). This study provides an experimental basis for efficient P removal by E-C adsorbent materials and suggests possible applications in rural domestic sewage.

Application Potential of Layered Double Hydroxides for The Treatment of Persistent Organic Pollutants

“…Xiao [27] pointed out that anions such as Cl -, HCO 3 − and HPO 4 2inhibited MNZ degradation. There are two reasons for this phenomenon : one is the consumption of free radicals ( • OH and SO4 • -) by these coexisting ions, and the other is that they increase the pH of the solution.Xu [28] prepared nano-zero-valent iron-loaded peanut shell biochar to degrade emerging pollutants PPCPs in water, and investigated the effect of inorganic anions on the degradation system. It was found that inorganic anions inhibited the degradation of tetracycline, and the inhibition intensity of inorganic anions on TC removal was HCO 3 ->Cl ->HPO 4 2->SO 4 2->NO 3 -.…”

Ligand Exchange Adsorbents for Selective Phosphate and Total Ammonia Nitrogen Recovery from Wastewaters

“…20,23,24 efficient, scalable, low cost, low maintenance, and provides the opportunity for nutrient recovery. 12,13 Wastewater nutrient and pollutant removal with adsorption technologies has been implemented at various treatment scales (nonsewered systems, 14,15 rural, 16 lab-scale, 17 household, 18 and full-scale wastewater treatment 19 ). Several classes of wastewater adsorbents have been described, including natural and synthetic zeolites and clays, polymeric ion exchangers, activated carbon and biochar, chitosan and cellulose, and metal oxide nanoparticles.…”

“…Ensuring the adoption of resource recovery requires the development of technologies to selectively separate nutrients from waste streams. Various techniques exist for nutrient removal such as biological methods, struvite precipitation, air stripping, membrane filtration, and adsorption. − Of these techniques, adsorption is a viable option because it is simple, efficient, scalable, low cost, low maintenance, and provides the opportunity for nutrient recovery. , Wastewater nutrient and pollutant removal with adsorption technologies has been implemented at various treatment scales (nonsewered systems, , rural, lab-scale, household, and full-scale wastewater treatment). Several classes of wastewater adsorbents have been described, including natural and synthetic zeolites and clays, polymeric ion exchangers, activated carbon and biochar, chitosan and cellulose, and metal oxide nanoparticles. − …”