Can human waste that ruins groundwater become bio-fertilizer instead?

On this World Water Day, management of wastewater and human waste remains challenging in some parts of the world.

The theme on World Water Day 2017 is 'Wastewater'. Photo: GMB Akash / icddr,b

Due to poor sanitation and hygiene, untreated waste and wastewater often come in contact with drinking water sources and transmit pathogens that cause major infectious diseases including diarrhoea.

A recent study conducted at icddr,b has shown that harmful pathogens in human waste can be deactivated by thermal treatment before the waste can be turned into bio-fertiliser.

Published in the Journal of Bacteriology and Parasitology, the findings demonstrated an ideal combination of culture techniques, time and temperature to neutralise human waste and cow dung. The first-ever study, proposing a standard sanitisation method that deactivated most of the identified pathogens, paves way for an alternative to polluting the environment.

“This finding has real-world implications. Our work can be a precursor to designing a pre-treatment or sanitisation unit in large biogas plant or large-scale organic fertiliser production factories,” says Dr Zahid Hayat Mahmud, principal investigator of the study and associate scientist at icddr,b.

Human waste, dubbed ‘faecal sludge’ when discarded in pits, is not always disposed of properly in sub-urban or rural areas with poor sanitation. In places, shallow faecal sludge pits are very close to the groundwater levels, which raises the risk of groundwater contamination by trickling waste from the pits.

“That is why people drinking from shallow tubewells often fall ill from diarrhoeal diseases,” says Dr Mahmud.

The river Buriganga has turned black due to garbage dumping. Photo: Rabiul Hasan / icddr,b

An earlier icddr,b study has shown that the rate of this contamination varies according to soil and water conditions. It suggested to maintain safe distance between shallow tubewells and pit latrines according to different soil conditions.

While discarding human waste remains challenging for areas with poor sanitation and other environmental factors, turning this waste into bio-fertiliser is useful but can be difficult.

Untreated human waste is already being used as fertiliser in different parts of Bangladesh and across the world but this can be dangerous for the environment and the people who handle it without proper caution.

Dr Mahmud explains that harmful pathogens including antibiotic resistant organisms may enter the food chain and contribute to the increasing problem of antibiotic resistance - when antibiotics become resistant to pathogens that cause diseases.

“With the new findings at hand, we need to conduct further studies to explore the ideal method to neutralise human waste before it can be feasibly turned into bio-fertiliser that will not contaminate the food chain,” he concludes.

MN

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