Role of organic compounds from different EPS fractions and their effect on sludge dewaterability by combining anaerobically mesophilic digestion pre-treatment and Fenton's reagent/lime

- AMD & F-L treatment was feasible in realizing sludge deep-dewatering.
- Protein-like substances in S-EPS were majorly responsible for sludge dewatering.
- The combination treatment disintegrated biopolymer and increased zeta potential.
- Through optimization conditions, moisture of sludge cake was reduced to 47.15 wt%.
- AMD & F-L conditioning was economically favorable.

Sludge deep-dewatering can be realized by adding Fenton's reagent and lime, but does have some limitations (mainly expensive costs) which restricted its application. Anaerobically mesophilic digestion (AMD) pre-treatment and Fenton's reagent/lime (F-L) as new approach are used to enhance the sludge dewaterability. In this study, the sludge physicochemical properties and the distributions and compositions of extracellular polymeric substances (EPS) were investigated in attempt to understand the observed changes in sludge dewaterability of two conditions: (1) AMD pretreatment; (2) Combining with F-L. The results indicated that AMD pretreatment changed the distributions of EPS fractions to promote the subsequent conditioning; and combination of AMD and F-L could significantly decline the specific resistance to filtration (SRF) by approximately 96.53%. Further studies of mechanism both revealed sludge particles were disintegrated into smaller particles and surface changes were neutralized, obtained a good dewaterability; and sludge dewaterability was significantly related to Tryptophan-like proteins and Aromatic proteins of soluble EPS. Additionally, the combination treatment decreased the moisture of dewatered sludge cake to about 47 wt% through using a controllable pressure filtration system. Furthermore, the preliminary economic analysis showed AMD & F-L treatment was economically favorable.

212