Abstract
Abstract Reed bed systems (RBS) have potential to treat wastewater, and being interested in such green wastewater infrastructures, an RBS has been installed for the first time in Bangladesh to treat faecal wastewater, which comes from a low-cost community latrine at a refugee camp in Cox's Bazar area. An anaerobic baffle reactor was set followed by the RBS, which was operated continuously for four months at five different retention times (3–7 days). The RBS was found to retain, on average, about 92% of 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD), 69% of and 52% of . Importantly, the effluent concentration met the national environmental standard for all except for . Thus the optimum hydraulic retention time in RBS has been selected to be 3 days when the ion has been reduced at maximum rate. High positive correlation () was observed between and concentrations in effluent water as well. The results of this study, thus, partly support the RBS as an effective green solution for faecal wastewater treatment.
Highlights
The demand for freshwater is increasing with increased world population, which is responsible for the conversion of the natural environment into constructed lands
The maximum values of chemical oxygen demand (COD) and BOD5 in the septic tanks (STT) have been found to be nearly 3,780 mg/L and 700 mg/L respectively, which are at least 60% more compared to their mean values and nearly 18 times higher than the sewage discharge standard of Bangladesh
When the effluent water has been passed to the anaerobic baffle reactor (ABR), the concentration of COD and BOD5 reduces to nearly 1,366 mg/L and 210 mg/L on average
Summary
The demand for freshwater is increasing with increased world population, which is responsible for the conversion of the natural environment into constructed lands. Along with the direct effect of land conversion, freshwater quality is degrading, and on the other hand, water demand is increasing. It is expected that freshwater stress may affect about 2.3 billion people by 2025 (World Health Organization 2006), and at least one-fourth of the world’s population by 2050 (World Water Assessment Programme (United Nations) 2003). Faecal sludge (FS) produced in these units needs to be periodically removed (Rohilla et al 2019). It is characterized by high solids, organic and enteric microorganism
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