Investigating the Effect of Vermifiltration with Different Bulking Agents on Some Important Properties of Municipal Sewage Influent

Abstract

Background: Farmers have been persuaded to use wastewater in agriculture due to drought and water deficiency. However, an important challenge is the environmental constraints.Methods: This study investigated the effect of vermifiltration on the properties of sewage influent. The sewage influent was obtained from the aerated lagoons of the Qahdarijan wastewater treatment plant, Isfahan Province, Iran. The sewage was mixed with Rice Husk (RH) and Wheat Straw (WS) as the bulking agents at three proportions (0%, 5%, and 10%v/v). Then, EarthWorm (EW) (Eisenia fetida) were added to the sewage sludge in two proportions (0 and 50 adult earthworms/6 kg sewage sludge).Results: The results showed a significant decrease in electrical conductivity (about 100% decrease compared to the control), total dissolved solids (up to 3 times in RH0+ EW treatment less than the control), total suspended solids (up to 90 times in WS10+EW and RH+EW treatments decrease compared to the control), biochemical oxygen demand (significant decrease in RH levels+EW compared to other treatments), and chemical oxygen demand (a reverse status was observed for WS and RH treatments, but the role of vermifiltration was considerable). The concentration of Pb was significantly decreased in WS when it was enriched with earthworms (about an 8% decrease compared to control), but a reverse status was observed for RS treatment.Conclusion: Vermifiltration may be an efficient tool for improving the properties of wastewater to use in agriculture, but more studies are suggested to evaluate different aspects of this technique.

Keywords

• wastewater
• heavy metals
• nitrates
• chemical oxygen demand
• public health