One of the most trivial ethical debates raged on my Facebook page after I posted about whether one should hang a toilet roll “over” or “under”. Of course, for those with a vertical toilet roll holder, it’s a moot point. But, silliness aside, there is an important moral debate to be had in the context of the environment and global sustainability surrounding what we do with human waste – urine and faeces.
Each of us produces around a litre of urine each day (estimates of the range from person to person across the globe say 500 to 1500 ml) and several hundred grams of faeces (minimum estimated at 50 grams with some people producing half a kilo). The liquid can be treated relatively easily in situ – and used as grey water for flushing. Solid waste is a different matter but in many parts of the world separator and composting toilets are becoming common place. Civil engineer Nityanand Singh Maurya of the National Institute of Technology Patna, in Bihar, India, recently suggested that we should certainly not view human excreta as waste to be processed and disposed. Despite our queasiness about the potential for spreading disease and the risk of accumulating heavy metals in the food chain if human faeces are used as crop fertiliser, there are ways to get around the problems
India and China have long used human waste as fertiliser and soil conditioner, it is after all mostly carbon, nitrogen and phosphorus, chemically speaking. But, in “the West”, we expend vast quantities of clean water to flush away our waste and yet more water to process it so that it can be dumped, as it were. There is great potential for the use of domestic eco-sanitation, particularly in rural areas and given the high-energy content of human faeces, conversion to biomass for power production is also a serious option.
Maurya suggests that for rural areas in the developing world, urine-diverting toilets make it relatively easy to collect urine separately and allow faeces to be composted. In urban environments, urine can again be collected separately and used as grey water while anaerobic treatment of faeces at the local level allows it to be used for fertiliser or biomass, or biogas for that matter. These approaches reduce demands on water supply and processing.
Singh Maurya, N., (2012). Is human excreta a waste?, Int. J. Environmental Technology and Management, 15 (3-6) 332. DOI:
Photo by thejbird
Maurya, N.S. (2012). Is human excreta a waste?, International Journal of Environmental Technology and Management, 15 (3/4/5/6) DOI: 10.1504/IJETM.2012.049231