South African Journal of Chemical Engineering (Oct 2022)
Innovative polymeric inorganic coagulant-flocculant for wastewater purification with simultaneous microbial reduction in treated effluent and sludge
Abstract
The current work introduces polymeric inorganic coagulant-flocculants; poly-ferric chloride (POFC) which prepared using iron-containing waste. Different POFCs were produced according to Fe/basicity ratio. Likewise, the efficiency of POFC for purification and microbial decontamination of domestic wastewater was evaluated using various doses of POFC coagulant-flocculants. The solid content of the prepared POFCs was ranged from 11.1 to 29.9%, and density was varied from 1.13 to 1.24 kg/L with the varying iron/basicity ratios. Analyses results of XRD, FTIR and SEM confirm formation of a new inorganic polymeric ferric chloride that it is not assumed simple mixture of components. Moreover, the prepared POFCs showed coagulant-flocculant characteristics; therefore it is employed for treating wastewater without introducing organic polymer. Both POFCs coagulant-flocculants showed removal efficiencies of 99, 99 and 91% for total suspended solids (TSS), turbidity and chemical oxygen demand (COD) from domestic wastewater. Also, a complete deactivation of the tested waterborne species in wastewater was achieved at 100 ppm dose of POFCs. At POFC dose of 150 ppm, it was found that the anaerobic microbes and sulfate-reducing bacteria in sludge were reduced by 99.9 and 98%, respectively. The deactivation anaerobic micobes and sulfate-reducing bacteria in the produced sludge by using POFC will result in odor reduction generated from sludge. Moreover, the integration between POFC-based coagulation and rapid sand filtration (RSF) lowers POFC dose use and showed a good efficiency for domestic wastewater purification and microbial decontamination. Finally, POFC-based treatment aids in the decrease organic and bacterial load that results in reducing disinfection use and declining disinfection by-products levels. Moreover, POFC-based treatment/rapid sand filtration is considered a well-located cost-effective train for purification of domestic wastewater and microbial decontamination in treated effluent and sludge and which can be reused for safe agricultural purpose.
