Abstract:

Trickling filters (TFs) are an ideal habitat for a diverse microbial community enriched with animals, or fauna. Fauna may have a beneficial impact on carbon-oxidizing TF performance when in proper balance, but an infestation can be also detrimental in several ways. State-of-the-art TF-process designs must incorporate mechanisms to manage macro fauna. Snail infestation is a common TF operational issue that can degrade effluent quality, adversely impact biosolids handling infrastructure, and be detrimental to costly process mechanical equipment. The most significant detrimental performance impacts include (1) nitrifying biofilm grazing, (2) process mechanical equipment damage due to snail shells, (3) excess biochemical oxygen demand exerted by snail bodies, and (4) increased suspended solids measurements owing to snail shells and bodies. Little information exists in the environmental engineering literature detailing the production rate of higher life-form predators, such as snails, in the TF process and a corresponding lack of information on the effectiveness of snail control techniques. Only case specific studies related to substrate transformation reaction rates or fauna mass weight measurement methods have been used to quantify macro fauna production. This review (1) describes macro fauna that are commonly found in TFs treating municipal wastewater, (2) surveys state-of-the-art snail removal technologies and their reported effectiveness, (3) identifies protocol for implementing various snail removal technologies, and (4) presents means for creating a database that can be used to establish snail production and removal in TF-based wastewater treatment plants.

Keywords: TRICKLING FILTER; SNAILS; MACRO FAUNA; BIOFILM GRAZING; PREDATION; NITRIFICATION; NITRIFYING TRICKLING FILTER; MUNICIPAL WASTEWATER TREATMENT; BIOFILM REACTOR

Document Type: Research article

DOI: 10.2175/193317708X335181