A Crawling Solution for Biowaste

By Nicola Gerber

In October of 2015, the United Nations defined 17 Sustainable Development Goals “to achieve a better and more sustainable future for all people and the world by 2030”. Nick Alcock deals with point six, “Ensure availability and sustainable management of water and sanitation for all”.

The expansion of the sewage systems cannot keep up with the rapid growth of developing neighbourhoods in rural areas. Nick Alcock, a Civil Engineer with over 20 years of experience in the water and sanitation sector and managing Member at Khanyisa Projects, is committed to tackle this problem. In collaboration with a managing contractor and small local businesses, it became possible to install 80,000 (and increasing) urine diversion double vault toilets (UD toilets) at the household level in rural areas in the eThekwini community (South Africa) since 2002. Due to the funding from the Bill & Melinda Gates Foundation (BMGF) options for disposal and recycling of the waste have been explored, which should not only eliminate the health risks for residents that handle the potentially pathogenic sludge, but also clarify the economic feasibility for the municipality. In this text, I will introduce you to the most exciting possibilities from my point of view.


Disposal by contractors

eThekwini Water and Sanitation (EWS) determined through a standard municipal procurement process a managing contractor, mandated to sub-contract seven informal businesses to undertake the work on site. Furthermore, the informal businesses participated in an accredited business training programme with the aim of making their businesses more competitive, compliant and ultimately sustainable. In order to evaluate success, additional mentoring was provided as well as household surveys to indicate customer satisfaction. However, reported attendance levels at the business training programme declined during the project. Only two out of the original seven businesses applied new skills and made their business more compliant. Almost all the businesses became financially dependent on the UD toilet emptying subcontract and were not viable when a new contract was not immediately in perspective. Despite the appointment of the managing contractor to take responsibility for the quality of service, customer satisfaction was as low as 58% in some areas.


This method of waste disposal does not seem to work, as these sub-contractors rely too much on the municipality's money and do not diversify into related sectors and therefore abstain from building a self-sustaining economic cycle. This also raises the question of financing; there is a demand for emptying the toilets, but so far, the product of this service cannot be sold further.

Photo Source: SAIC, 24.03.2022
Photo Source: SAIC, 24.03.2022

Black Soldier Fly Biowaste Processing

The second form of disposal could improve this funding dilemma, it takes place with the help of a small fly, or rather its larvae. These feed on all kinds of organic material and are used in farm-like facilities to reduce total waste. The principle described by the Eawag – Swiss Federal Institute of Aquatic Science and Technology is quite simple: it relies on simple technology and on workers who do not require any special training.


The faecal waste is mixed with food waste and pre-processed into a sludge-like mass. Larvae are bred from an initial population of Black Soldier Flies and later added to the sludge. After approximately two weeks, the now-adult larvae are separated from the residue, now similar to compost which contains nutrients that help to reduce soil depletion. After the larvae have done their work, they can be processed into excellent animal feed or oil, and finally sold. 


Obviously, it does not sound very appetizing if the fish or poultry that we eat were previously “fed with faeces”. However, feeding waste has been shown to inactivate disease transmitting bacteria such as Salmonella spp.


With this processing method, a waste reduction of up to 80% of the biowaste is made possible. Furthermore, the toilet emptying, transportation and process can be reduced by selling the larvae. With initial funding, these facilities could be run by private companies which in return create more jobs opportunities. These plants would create a demand for organic waste, which would encourage communities to minimize the soiling of toilets with non-organic material to increase the quality of the sludge. Whether this method can become established will probably only become clear in the next few years. However, various examples in the Philippines show a promising future. 


Unfortunately, toilets and sanitation are not as often in politicians' campaign pictures as new schools or wells, which is why Nick Alcock's work is so significant.


Because one thing is certain: sanitation and its functionality must be improved!