Investigation the effect of vermifiltration with different bulking agents on some important properties of municipal sewage influent

The growers have been persuaded to use wastewater in agriculture due to drought and water deficiency more than ever. However, an important challenge is its environmental constraints.

In this study, the effect of vermifiltration on properties of sewage influent was investigated. The sewage influent was obtained from the aerated lagoons of Qahdarijan wastewater treatment plant, Isfahan, Iran. It was mixed with rice husk (RH) and wheat straw (WS) as the bulking agents in three levels (0, 5 and 10%v/v). Earthworm (Eisenia foetida) was added to the sewage sludge in 2 levels [0 (EW0) and 50 (EW) adult earthworms /6 kg sewage sludge].

The results showed  a significant decrease in EC (about 100% decrease compared to the control), TDS (up to 3 times in RH0+ EW treatment less than the control), TSS (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), 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 was enriched with earthworms (about 8% decrease compared to control) but a reverse status was observed for RS treatment.

It is imagined that vermifiltration may be considered as an efficient tool for improving the properties of wastewater in order to use in agriculture but more studies are suggested for evaluation of different aspects of this technique.