Effects of volumetric load in an anaerobic sequencing batch biofilm treating industrial saline wastewater

Abstract

Mustard tuber wastewater is of high salinity ([Cl⁻¹] = 18∼23 g L⁻¹), high organic content (chemical oxygen demand, COD = 4000 ± 100 L⁻¹) and biodegradability (BOD₅/COD ≈ 0.5). The anaerobic sequencing batch biofilm reactor (ASBBR) pre-treatment, an important step to meet national discharge standard, was applied to reduce much of the organics in mustard tuber wastewater. The experiment for the effect of the volumetric load on ASBBR treating mustard tuber wastewater was conducted at different hydraulic retention times (HRTs) and volumetric exchange ratios (λ). The ASBBR operating at 50% biomass density, 30 °C, influent COD concentration of 4000 ± 100 mg L⁻¹ and pH value of 7.0 ± 0.2, the effluent COD concentration increased from 0.22 to 4 kgCOD m⁻³d⁻¹ when the volumetric load increased from 100 to 1520 mg L⁻¹. The effluent COD concentration differed when adopted different HRT and λ under the same volumetric load. And given certain influent levels, a higher performance of ASBBR could be achieved at a lower value of HRT and λ. The optimal operational load could be determined by limiting the COD concentration under different discharge conditions, based on the results obtained in experiments.

Keywords:

• anaerobic sequencing batch biofilm reactor (ASBBR)
• hydraulic retention time
• industrial saline wastewater
• volumetric exchange ratio
• volumetric load

Acknowledgement

The work reported here was financially supported by the China National Science Foundation Program (Grant Number: 51008318).