Effect of Organic Loading and Nitrogen Concentration on the Efficiency of the Sequencing Batch Reactor (SBR) System with Electroplating Wastewater (EPWW)

Abstract

The study was concerned with the effects of the organic loading as food/microbe (F/M) and nitrogen concentration as BOD₅: TN on the sequencing batch reactor (SBR) system efficiency and performance with 1:5 diluted-electroplating wastewater (EPWW) solutions.  The results showed that chemical oxygen demand (COD) and biological oxygen demand (BOD₅) removal efficiencies were almost the same with the organic loadings of 0.125-0.375 kg BOD₅/m³.d. The CN^- and Zn²⁺ loadings of 1.2-2.9 and 1.6-4.0 g/m³.d did not show strong repression effects to the COD and BOD₅ removal efficiencies. In addition, the high Zn²⁺ removal efficiency level of 94-96% was detected. Moreover, the system did not show any difference in Zn²⁺ and COD removal efficiencies at the BOD₅: TN ratios of 100:5-100:10. Urea and (NH₄)₂SO₄ could be used as the nitrogen source of 1:5 diluted-electroplating wastewater solution. The  highest COD, BOD₅, Zn²⁺, CN^-, Total Kjeldahl nitrogen (TKN) and total nitrogen (TN) removal efficiencies of  98.0±0.2, 97.0±0.7, 97.7±0.1, 93.3±1.2, 86.5±1.1 and 80.9±0.5%, respectively, were detected at the BOD₅:TN ratio of 100:10 and (NH₄)₂SO₄ was used as the nitrogen source. The system also showed good bio-sludge performance with the Sludge Volume Index (SVI) and Sludge Retention Time (SRT) values of 51±4 mL/g and 29±3 days, respectively.