Assessing the effect of filter bed material on the survival of earthworms in vermifilters

Abstract

Vermifiltration is a relatively new technology in waste water treatment and despite the extensive research available it is not being used as a major water treatment technology. It utilizes earthworms in a filtration set up to treat domestic waste operating at a certain range of physical conditions i.e. temperature and moisture content. This report is on research of the effect of the filterbed material on the survival of earthworms in the vermifilter and it compared three different materials. Three filters (1, 2, 3) were set up using PVC columns of a diameter of 110mm with a layer of gravel, a layer of sand and a layer of filter bed material. For filterbed material, filter 1 had sawdust, filter 2 had a mixture of shredded newspapers and sawdust while filter 3 had shredded newspapers. From the experiment, it was determined that sawdust is the more suitable filterbed material as only a single worm died. It also provided a higher removal efficiency for BOD5, COD, TSS and FC. The percentage removal for the previously mentioned parameters for filter 1 were 94%, 88%, 97% and 99% respectively. For filter 2, the percentage removal values were 93%, 88%, 97% and 99% respectively. For filter 3, the values are 93%, 87%, 96% and 99% respectively.