Optimization and effect of powdered activated carbon addition on commingled chemical industrial wastewater treatment in a sequencing batch reactor

Abstract

In this study, commingled chemical industrial wastewater was treated using a sequencing batch reactor with powdered activated carbon (PAC–SBR). The performance of the PAC–SBR system was investigated under various dosages and feeding frequencies. Results showed that a PAC dosage of 2 g PAC/L-reactor and a feeding frequency of 0.25 g PAC/L-reactor to 0.5 g PAC/L-reactor per 3.5–7 d maintained a stable long-term performance during operation. The effects of PAC addition were also considered. Removal of organic matter in the PAC–SBR system demonstrated synergistic effects of biodegradation and PAC adsorption. The system with PAC had better sludge volume index values (100–200) than that without PAC (150–250). This result suggested that the sludge settling characteristic was improved. Hence, PAC addition was proven to increase biomass in the PAC–SBR system, which improved the removal of chemical oxygen demand through biodegradation. Furthermore, the excitation–emission matrix spectrum of organic matter showed that compounds in raw wastewater that contains aromatic rings, heterocyclic ring structures, and bicyclic aromatic structures were partially removed by biodegradation and PAC adsorption. The organic acid-like compounds, which were recalcitrant to biodegradation, were adsorbed via PAC. The results of organic matter fractionation showed that compounds in transphilic neutral and hydrophilic fractions were easily transformed through biodegradation, whereas compounds in hydrophobic fractions were adsorbed by PAC.

Keywords:

• Chemical industrial wastewater
• Powdered activated carbon
• Adsorption
• Optimization
• Organic matter fractionation

Acknowledgment

This work was supported by the Science and Technology Support Project of Tianjin, China (Grant No. 12ZCZDSF01800).