Performance of constructed wetland integrated with sand filters for treating high turbid water for drinking

Abstract

The feasibility of constructed wetland integrated with sand filters (CW-SFs) for treating high turbid water for drinking was investigated. Turbid water of >1,000 NTU from Nadosaito dam in Monduli District, Tanzania was used. Along with turbidity; faecal coliform (FC), chemical oxygen demand (COD), total suspended solids (TSS) and nitrate removal were investigated. Furthermore, determination of optimal retention time for pollutants removal to acceptable levels was assessed at retention times of 0.5 to 5 days. Horizontal subsurface flow constructed wetland (HSSFCW) was used as pretreatment stage prior to biosand or slow sand filters. Results showed that HSSFCW produced effluent turbidity of <10–50 NTU at retention time of 3 days. Moreover, integrated CW-BSF needed a total retention time of 5 days to produce effluent of turbidity (0 NTU), FC (0 CFU/100 ml), COD (6.25 mg/L), TSS (0.5 mg/L) and nitrate (4.2 mg/L) whereas, CW-SSF needed 7 days to produce effluent of turbidity (0.6 NTU), FC (0 CFU/100 ml), COD (6.5 mg/L), TSS (1 mg/L) and nitrate (1.79 mg/L), which met drinking water standards of Tanzania Bureau of Standards (TBS) and World Health Organization (WHO). CW-BSF showed better performance than CW-SSF therefore, its application can enhance the availability of potable water in Tanzania rural communities.

Performance of inclined plates settler integrated with constructed wetland for high turbidity water treatment

“…Results from Table 1 show that EC and TDS were increasing from influent values of the IPS to the effluent values of the CW. This increasing trend of EC and TDS in the IPS-CW treatment systems might have been caused by the dissolution of ions during the breakdown of contaminants in water, as suggested by Mtavangu et al (2017).…”

“…In the IPS-CW treatment system, pH showed a general increasing trend from the inlet of the IPS to the outlet of the constructed wetland at all set flowrates as shown in Table 1. This trend might be due to the anaerobic decomposition of organic matter and the dissolution of inorganic compounds in water (Masbough et al 2005;Mtavangu et al 2017).…”

“…Constructed wetlands are low-cost technologies that use locally available materials, simple to operate, repair, and maintain but also require low energy (Mtavangu et al 2017;Njau et al 2011). The presence of macrophytes, substrates and microbial community results in complex inter-connected physical, chemical and biological mechanisms in removing water contaminants (Vymazal 2007;Zhang et al 2012).…”

“…However, external factors like pH, temperature, dissolved oxygen, hydraulic loading rate and hydraulic retention time affect pollutant removal mechanisms (Deng et al 2011;Wang et al 2012aWang et al , 2012b. Most of the studies use CW for wastewater treatment but also a few studies have documented the use of CW for improvement of river waters, dam waters, and stormwater runoff for drinking water purposes (Ewel 1997;Froebrich et al 2006;Huang et al 2007;Kadlec & Wallace 2008;Kurzbaum et al 2012;Mtavangu et al 2017). Considering the targeted location (rural area), material availability and accessibility, the water quality problem within the studied earth dam, and the reported capacity of the CW to deal with such contaminants (Eliakimu et al 2018).…”

Pretreatment of Real Wastewater from the Chocolate Manufacturing Industry through an Integrated Process of Electrocoagulation and Sand Filtration

“…For disinfection of wastewater reuse, the turbidity and suspended solids must be reduced to prevent the hiding of pathogens and organisms that hide behind these solids. Currently, the most widely used process to remove residual TSS (total suspended solids) is treated effluent filtration [24,25]. The main mechanisms contributing to the removal of suspended solids in sand filters are cast [22,26].…”