New insights into the cation exchange resin-driven carbon migration and recovery from waste activated sludge: Mass transfer environment and cation exchange force

Abstract

Innovative cation exchange resin (CER)-driven anaerobic fermentation showed significant promise for enhancing carbon recovery from waste activated sludge. However comprehensive microscopic studies on the responses of cation exchange environments have been scarcely reported. This study clarified the transport mechanism of divalent cations within the “sludge→CER→cation exchange groups” pathway, along with comprehensive evaluations of carbon migration and recovery. It demonstrated that the sludge suspension solid (SS) and cation exchange groups dominantly determined the CER treatment performance, instead of CER pore structure. The –COOH exhibited the strongest electrostatic-adsorption capacity among various cation exchange groups. Such mass transfer environment modification and cation exchange groups regulation could improve ionic charge removal to 4.91 mmol e−/g VSS. By macroporous-COOH CER treatment at sludge SS of 20 g/L, the overall carbon migration reached 192.66 mg C/g VSS (44.98 %). As such, the ultimate carbon recovery elevated to 120.34 mg C/g VSS (28.10 %), against the lower performances of 13.91–32.97 mg C/g VSS without cation exchange environment regulations. The cation exchange groups showed correlations with carbon migration, biotransformation, and recovery, as indicated by grey relational analysis degrees of 0.48–0.66. Simultaneously, by adopting the optimized regulation strategy of CER-driven anaerobic fermentation, the equivalent economic income raised to 410.93 CNY/ton sludge SS.