Heavy metal inhibition on an alternating activated sludge system and its comparison to conventional methods: case study of Cu2+

Abstract

In order to understand the behaviour of wastewater treatment plants with heavy metal presence, this study evaluates the treatment process in the presence of heavy metals (Cu2+ as a case study) and compares it with the absence of heavy metals. An activated sludge model is improved by means of incorporating other novel inhibitory kinetic and settler models for this evaluation. To achieve this goal, a simulation algorithm is developed using the MATLAB code to detect any heavy metal influence on the aerobic and anoxic growth of heterotrophic and autotrophic biomass. The code also allows for a comparison of treatment plant performance with and without Cu2+ in both conventional and alternating systems. The results reveal that the presence of heavy metals, in this study for Cu2+ at 0.5 mg/L, in a biological treatment system, has an inhibitory effect on the heterotrophic bacteria but more so on the autotrophic bacteria growth and it prevents nitrification and denitrification, thus having a negative effect on the nitrogen removal in the alternating systems. HIGHLIGHTS A simulation algorithm is developed using the MATLAB code.; The wasterwater treatment plants process is evaluated in the presence of Cu2+.; An ASM is improved by incorporation of inhibitory kinetic and settler models.; Heavy metal influence on heterotrophic and autotrophic biomass is assessed.; WWTP performance in conventional and alternating systems is determined.;

Keywords

• alternating systems
• asm3
• autotrophs
• copper inhibition
• heterotrophs