Co-treatment of stabilized landfill leachate and municipal wastewater in a granular activated carbon-sequencing batch reactor (GAC-SBR)

A laboratory-scale granular activated carbon-sequencing batch reactor (GAC-SBR) was used to co-treat stabilized landfill leachate with municipal wastewater. GAC-SBR was studied for the different mixing ratios of leachate and municipal wastewater at different hydraulic retention time (HRT). GAC dose (5, 10, 15 and 20 g/L) was optimized for COD reduction with a contact time of 22 h. GAC-SBR treatment efficiency was assessed on mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), turbidity, chemical oxygen demand (COD), ammonia, nitrate, and phosphate removal. Univariate ANOVA was applied to test the statistical significance of treatment at different leachate:wastewater ratios. Results showed that the increase in GAC concentration led to an increase in the removal of COD and ammonia from stabilized landfill leachate. Adsorption efficiency decreased or remained constant after 15 g/L GAC. GAC-SBR was efficient in removing COD (83%) and nutrients (80-90%) from stabilized landfill leachate at 10 d HRT. Univariate analysis of variance (ANOVA) highlighted that there was a statistically significant difference in the treatments for the mixing ratio tested. GACSBR results showed that treatment efficiency was dependent on landfill leachate concentration and hydraulic retention time (HRT). Coupled treatment tested exhibited a high potential for co-treatment of leachate and municipal wastewater. However, the effluent after treatment could not achieve a complete or very high level of COD, nutrients and turbidity removal which necessitates the incorporation of physico-chemical processes such as coagulation, electrocoagulation, membrane filtration etc. as post-treatment options. Further studies in this direction along with exploring the longevity of GAC in SBR would provide useful information for effective landfill leachate treatment.