Mr. Madzaramba is a Water Resources Engineer with experience in wastewater reuse, decentralized water and wastewater systems focusing on increased water supply, environmental sustainability and improved public health. We are pleased to share his interview in this two-part series on non-sewered sanitation.
The following questions were discussed:
- How would you convince decision-makers to accept non-sewered sanitation versus traditional/conventional sewerage sanitation?
- Can you list different alternatives or approaches towards unconventional sanitation?
1. How would you convince decision-makers to accept non-sewered sanitation versus traditional/conventional sewerage sanitation?
There are three arguments that I would offer:
- Water savings or water-use demands. Piped sanitation systems typically require large volumes of potable water – water which in much of the world is in short supply. Furthermore, this potable water requires treatment which is quite expensive. So, my argument would be that traditional sewerage infrastructure, including (fluid) conveyance is expensive, utilizes high quality/precious water (simply to convey sewage) and is a challenge to maintain. I would simply ask – is this the best use of potable water? I would share that, by adopting non-sewered systems, there is much less reliance on water supply – a heightened benefit in areas with no easy, or expensive access to raw water supply. Basically, non-sewered systems reduce water demand, which in turn decreases the overall costs to the utility.
- Financial investments. Second, I would bring up the fact that non-sewered sanitation often requires lower investment costs (by close to five times!) when compared to conventional sanitation systems. Furthermore, non-sewered sanitation does not require large, long pipes and disturbances for the associated excavations. Lastly, piped sanitation systems necessitate expensive renewal or replacement over time, resulting in greater life-cycle costs – expenditures that are likely above the financial means of many municipalities or utilities.
- Environmental sustainability. I’m of the opinion that traditional piped sanitation systems, which are prevalent in the cities of Africa, are unsustainable. Leakages of raw sewage, in densely populated areas, is not uncommon. And, besides the risk to citizens riparian to the leakages, the sewage often finds its way into groundwater, rivers and streams. On the contrary, non-sewered sanitation systems minimizes potential contamination of water resources, while limiting the disruption to the ecosystem due to the disposal of partially treated wastewater in the environment. All too often, in many cities, partially treated wastewater is flagrantly discharged to the environment. With non-sewered sanitation, disposal of faecal sludge is done on-site, which limits contamination of the ecosystem. As I said earlier, sewered sanitation often discharges wastewater to water resources resulting in eutrophication, death of fish, etc. Moreover, conventional systems are susceptible to natural disasters (i.e. earthquakes, flooding, etc.), that could easily damage the infrastructure and result in even greater pollution of receiving water bodies.
2. Can you list different alternatives or approaches towards unconventional sanitation?
In terms of approaches, concepts such as ecological sanitation toilets, that ensure resource revitalisation and reduce the impact of faecal sludge in the environment, can be adopted. An ecosan toilet, still considered “unconventional sanitation”, is designed to store and compost human faeces for beneficial use such as fertiliser for personal farming.
Therefore, if a utility can access these type technologies, there is an opportunity to lessen stress on natural resources. Also, recycling of nutrients, considering that medium to large scale farming can be an expensive enterprise, especially when requiring synthetic fertilizers, provides cost savings. This provides an opportunity for reutilising what may be the most nutritious forms of fertiliser, which is basically beneficial use of human waste for production.
Other approaches include low-flush latrines. These are basically latrines yet equipped with a flushing mechanism which replaces the traditional septic tank. The idea being to commence treating the water immediately after the latrine has been used. It is a cost-efficient technology which eliminates the emptying costs associated with septic tanks, because it is a package that collects treats and disposes faecal sludge. There are also technologies such as urine diversion flush toilets (UDFT) which facilitate the separation of human waste products, as well as enabling the system to treat the waste products.
In conclusion, it is essential to consider low-cost, alternative sanitation strategies. These enable the utility to maximize use of, and protect water resources, with the side benefit of being more economical.