Faecal sludge treatment by vermifiltration: proof of concept

The objective of this study was to determine if composting worms and their cocoons are able to survive in and digest faecal sludge. Eighteen vermifilters with different worm and cocoon densities were set-up, fed with faecal sludge (from portable pour-flush toilets) and ran for 38 days. Samples of the sludge, effluent and vermicompost were analysed for pH, total solids, chemical oxygen demand, faecal coliforms and Ascaris spp. number and viability. Worm and vermicompost mass, and cocoon numbers were assessed at the end of this period. It was found that the composting worms survived in these conditions and cocoons hatched. The validity of the sludge analysis results are questioned in this paper and without these results only estimates of effluent treatment and solids conversion could be made. Although this study was not completely definitive it has shown that worms are capable of converting faecal sludge into vermicompost and cocoons hatch in its presence. This trial was undertaken in India

The development of an onsite sanitation system based on vermifiltration: the ‘tiger toilet’

This paper describes the development of a novel onsite sanitation system based on vermifiltration, the ‘Tiger Toilet’. Initial laboratory experiments demonstrated that feed distribution was not required, a worm density of 2 kg/m2 could be used, worms preferred wetter environments, and system configuration did not affect effluent quality. Installing the first prototype in the UK proved that the process functioned when scaled, i.e., chemical oxygen demand and thermotolerant coliform reduction were found to be comparable with the laboratory results. Ten prototypes were then tested by households in rural India; all were working well after six months. The vermifilters were processing the amount of faeces entering the system on a daily basis, so faeces was not accumulating. It was estimated that they would require emptying after approximately five years, based on the depth of the vermicompost generated. With further development, it is believed that the Tiger Toilet has the potential to become a superior form of onsite sanitation, when compared with traditional onsite sanitation technologies

Technical and user evaluation of a novel worm-based, on-site sanitation system in rural India

The technical performance and user acceptance of a novel on-site sanitation system based on vermifiltration was tested for over 12 months in rural India. Ten households (mean household size = 5.6 people) who had previously practised open defecation trialled a pour flush toilet linked to a vermifilter, together known as a ‘Tiger Toilet’. Technical parameters which were monitored over this period included: usage, temperature, accumulation of faecal matter and vermicompost, presence of worms, and influent and effluent quality. User satisfaction was evaluated relative to a baseline survey and through focus group discussions. The vermifilters processed human waste products effectively in a real life scenario. After 12 months there was little accumulation of faecal solids (0–10 per cent surface coverage) and effluent quality was good (chemical oxygen demand reduction = 57 per cent, faecal coliforms reduction = 99 per cent). Vermicompost accumulation was low and suggested that emptying would only be necessary every five years. User satisfaction levels were high, with 100 per cent of respondents being either very satisfied (60 per cent) or satisfied (40 per cent) with the ‘Tiger Toilet’. The main reasons given were the use of worms and the lack of smells