Microbial water quality improvement by small scale on-site subsurface wetland treatment.

It has been demonstrated that large constructed wetlands used for domestic wastewater treatment are useful in the reduction of enteric microorganisms. This study evaluated the ability of three small-scale, on-site subsurface wetlands with different vegetation densities to remove total coliforms, fecal coliforms, coliphage, Giardia and Cryptosporidium. These wetlands were found to be equally efficient in the removal of enteric bacteria and coliphage as larger constructed wetlands. Giardia and Cryptosporidium were usually undetectable after passage of the wastewater through the subsurface wetlands. Coliphage removal increased with increasing vegetation density.