Academic journal article Journal of Sustainable Development

The Effectiveness and Safety of Vermi-Versus Conventional Composting of Human Feces with Ascaris Suum Ova as Model Helminthic Parasites

Academic journal article Journal of Sustainable Development

The Effectiveness and Safety of Vermi-Versus Conventional Composting of Human Feces with Ascaris Suum Ova as Model Helminthic Parasites

Article excerpt

Abstract

Composting toilets have been promoted for management of human waste at remote sites in parks and alpine areas of recreation, but they may not be effective for producing a stable and safe end product. Vermicomposting has been shown to result in a more degraded final product but its effectiveness for pathogen destruction was unclear due to conflicting information in the literature. This study sought to resolve the debate on whether or not vermicomposting could produce a hygenic end product that would be safe for disposal locally. Vermicomposting was tested for destruction of the model pathogens, helminthic parasites, in an experiment with highly concentrated and viable Ascaris suum (2626±1306 ova/g, 61.6±8.7% viable) inoculated into fecal matter and coir (30:70 ratio) with and without Eisenia fetida worms. After 90 days at 19±3 °C six, eight, and 12 worms were found alive with no significant difference between treatments or through time found in TS% (12-15%), ova concentration and ova viability. A 100 times reduction in the concentration of Escherichia coli resulted from the worm treatment versus the control. Significantly higher nitrate (22 735±4 741 mg/kg NO^sub 3^^sup -^) and lower pH (pH 4.60±0.01) were found in the treatment as compared to the control (5 078±2 167 mg/kg NO^sub 3^^sup -^) (pH 6.56±0.30). Despite these improvements in fecal matter processing, vermicomposting was found ineffective at reducing Ascaris suum ova concentration and viability. Decentralized vermicomposting can efficiently stabilize and mature fecal matter; however prior to unrestricted end product use, an additional sanitation step is necessary.

Keywords: vermicomposting, human waste.. Iscaris suum, helminthic parasites, E. coli, nitrate

1. Introduction

Management of human waste using waterless technology is often the only option in remote locations. Additionally, composting toilets are being adopted in some urban areas, since they are perceived as safe and effective, although there is little on going monitoring to prove this. The ideal onsite human waste treatment system would be a continuous flow, one step process to produce stabilized, sanitized and mature end products that can be handled without health risks and disposed onsite without environmental impacts, bringing about, at very low cost and risk, production of a soil amendment that could be used for rehabilitation projects. The waterless and waste reuse aspects of composting toilets make them an attractive sustainable technology.

Despite popular perception, Hill and Baldwin (2012) indicate that composting toilets fail to deliver these objectives. Urine diverting dehydrating toilets (UDDTs) divert urine, evaporate moisture, and require ash amendment in order to reduce pathogens through desiccation and alkalization and are considered to be an improved design over latrine composting toilets. Despite the focus on pathogen destruction over stabilization, 31% of samples from Bolivian UDDTs that met World Health Organization (WHO) guidelines for UDDTs (high pH, low moisture, and long storage times), still contained viable Ascaris lumbricoides ova indicating that UDDT systems are not reliable sanitization systems (McKinley, Parzen, & Guzmán, 2012).

Although vermicomposting has not been approved by Canadian or US federal agencies as a pathogen reduction and stabilization pathway, it has been shown that vemicomposting (Eastman et al., 2001) and urine diverting vermicomposting toilets (Hill & Baldwin, 2012) may have the capability to deliver on all of these objectives (stabilization, maturation, and sanitization). By diverting urine, fecal matter and toilet paper become a suitable feedstock for decentralized vermicomposting, a process that was shown, by Hill and Baldwin (2012), to produce sanitized (low E. coli), mature (Solvita® 4±0) and stable (VS 60±10%) solid end product from human excrement, as has been shown similarly in numerous other studies including Bajsa, Nair, Mathew, Ho (2003) (sewage sludge), Yadav, Hait, Tare (2007) (source separated fecal matter), Benitez, Nogales, Elvira, Masciandaro, Ceccaniti (1999) (sewage sludge), and others for numerous animal manures and industrial wastes as reviewed by Sinha, Herat, Bharambe (2009) and Edwards, Arancon, Sherman (2011). …

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