Performance of an anaerobic baffled reactor (ABR) as a hydrolysis-acidogenesis unit in treating landfill leachate mixed with municipal sewage

A study on the performance of an Anaerobic Baffled Reactor(ABR) as a hydrolysis-acidogenesis unit in treating the mixed wastewater of landfill leachate and municipal sewage in different volumetric ratios was carried out. The results showed that ABR substantially improved the biological treatability of the mixed wastewater by increasing its BOD₅/COD ratio to 0.4–0.6 from the initial values of 0.15–0.3. The formation of bar-shaped granular sludge of 0.5–5 mm both in diameter and length with an SVI of 7.5–14.2 ml/g was observed in all compartments of the ABR when the organic loading rate reached 4.71 kgCOD/m³ · d. The effects of the ratios of NH₄⁺-N/COD and COD/TP in mixed wastewater on the operational performance were also studied, from which it was found that a reasonable NH₄⁺-N/COD ratio should be lower than 0.02, and the phosphorus supplement was needed when the volumetric ratio was higher than 4:6 for stable operation of ABR.