**4. Findings and conclusions**

Design hydraulic retention time was 1 hour 40 minutes, with a hydraulic loading rate of 163 l/m<sup>2</sup> /hour. The design parameters of the vermifilter are shown in **Table 2**.

The designed vermifilter and control biofilters were efficient in treating domestic sewage for the selected chemical parameters. Analysis of variance revealed that the vermifilter and control filter significantly (p < 0.001) treated the chemical properties of the domestic sewage water (**Table 3**).

All chemical parameters levels (pH, BOD, NO3, PO4 and chlorides) of treated sewage using the two filters were significantly different from the untreated sewage. However, no significant differences were observed on the chemical properties of


### **Table 2.**

*Parameters of the designed vermifilter.*


### **Table 3.**

*Analysis of variance of the efficiency of the vermifilter and control biofilter in treating domestic sewage on the selected chemical parameters.*

sewage water treated using the two filters. The percentage range reduction in BOD on the VF was 68–97% whilst in the CF it was 76–98%, PO4 in VF it was 90–99%, in the CF 95–98%. An increase was observed in nitrates in the VF of 96–98% and CF 62–82%.
