Food Waste Disposal Units and their possible impact on sewer rat populations in the United Kingdom

Abstract

Sewer Rats (Rattus norvegicus) are opportunist occupiers of parts of underground sewerage networks. Their occupation in part depends upon their ability to scavenge food particles from faecal matter in the sewer flow. Food Waste Disposal Units, also called Garbage Grinders or Waste Macerators, are relatively uncommon in the United Kingdom (UK) but may become more common as pressure is put on other methods of waste disposal. Since these units put undigested food into the sewer network, some assessment needed to be made on any potential impacts on the sewer rodent population. This is important since policy relating to the acceptance of waste disposal units (WDUs) was based upon outputs. A selection of WDUs were acquired and a series of standardised tests were performed on a variety of food groups to assess whether the output of these units would represent a potential food resource for rats in sewers. These results are presented graphically in the text, and show that a large proportion of the output would be available to rats.

Impacts and managerial implications for sewer systems due to recent changes to inputs in domestic wastewater – A review

“…Channon et al (2013) evaluated particle sizes potentially available to rats (2e4 mm) from 5 different types of FWD models available on the U.K market and concluded that 50e69% of the total solids ground were within that range. Results from grinding tests have led some authors to conclude that certain types of food wastes are not properly ground by FWDs, examples of such material are egg shells and bones (Galil and Shpiner, 2001); fish (Bolzonella et al, 2003;Channon et al, 2013) and lettuce (Kegebein et al, 2001). However, Lagerkvist and Karsson (1983) determined that it was possible to grind diapers/nappies in an FWD-model.…”

“…Channon et al (2013) In-building drainage pipes directly receiving output from five different FWD models…”

“…No significant impact could be observed apart from the attachment of a thin biofilm on the pipe wall. Channon et al (2013) processed food waste rich in FOG in a laboratory setting for five different commercially available models of FWDs. In the effluent from all five models, clumps of meat fibres and FOG were observed to adhere to in-building drainage pipes connecting to the FWD.…”