![]() ![]() Three potential P recovery scenarios (PR1‒PR3: struvite, vivianite, and treated sludge) and corresponding current-day scenarios (CT1‒CT3 and CF) were considered. Here, we evaluated the environmental sustainability opportunity and socio-economic costs of recovering P from sewage sludge by replacing the current-day treatments (CT sludge treatment and landfill) and P chemical fertilizer application (CF) in China using life cycle assessment and life cycle costing methods. The low operating cost and reduction in chemical usage make it an efficient, sustainable alternative to the conventional treatment processes currently used for complex wastewater.Īlthough phosphorus (P) recovery and management from sewage sludge are practiced in North America and Europe, such practices are not yet to be implemented in China. The pH regulator dosage and operating costs were just 9.7 and 1.4%, respectively, of what is required by classic Fenton. The closed iron cycle avoided iron loss and iron sludge accumulation during operation. The bioelectrode system generated 13 ± 3 mg/L dissolved Fe(II) and 5 ± 0.4 mg/L H 2 O 2 for the Fenton reaction unit. Dissolved organic carbon and 22 specific recalcitrant organics were removed by 99% and between 78 and 100%, respectively. The system's self-alkalinity buffering also waives the need for pH regulators. Our new system includes a novel three-chamber microbial electrolysis unit and Fenton reaction unit, where Fenton reagents are generated by biotic and abiotic cathodes, while the bioanode simultaneously degrades biodegradable organics from the wastewater. This paper describes a new method for Fenton treatment of complex wastewater without additional dosing of Fe(II) and H 2 O 2, without iron-sludge accumulation, and with less consumption of pH regulators, using a novel bioelectrode system. This study is important from a P recovery point of view, but also because iron addition can play a crucial role in future resource recovery wastewater facilities.Ĭonventional Fenton treatment is fundamentally impractical for large-scale applications, as the consumption of Fe(II), H 2 O 2, and pH regulators and the accumulation of iron hydroxide sludge are very costly. Since quantification of vivianite in DS is complicated, previous studies were reviewed and we proposed a more accurate Mössbauer spectroscopy analysis and fitting for sludge samples. No negative impact on the nitrogen removal, biogas production, COD removal or dewaterability was observed. Following the Fe dosing increase, P in the effluent and H2S in the biogas both decreased: 1.28 to 0.42 ppm for P and 26 to 8 ppm for H2S. These differences could have an impact on the subsequent magnetic separation. Interestingly, analyses suggest that several types of vivianite are formed in the WWTP, and could differ in their purity, oxidation state or crystallinity. This increase was directly proportional to the increase of Fe in DS, suggesting that vivianite could be favored not only thermodynamically, but also kinetically. The share of phosphorus present as vivianite in the DS increased from 20% to 50% after the increase in Fe dosing, making more phosphorus available for future magnetic recovery. Higher Fe dosing is not only relevant for P-recovery, but also for maximal recovery of organics from influent for e.g. To study the production of vivianite in digested sludge, the quantity of Fe dosed at the WWTP of Nieuwveer (The Netherlands) was increased (from 0.83 to 1.53 kg Fe/kg P in the influent), and the possible benefits for the functioning of the WWTP were evaluated. Recent studies have demonstrated that phosphorus can be magnetically recovered as vivianite (Fe(II)3(PO4)2*8H2O) from the digested sludge (DS) of Waste Water Treatment Plants (WWTP) dosing iron. ![]() The recovery of phosphorus from secondary sources like sewage sludge is essential in a world suffering from resources depletion. ![]()
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