ALTERNATIVE SOLUTIONS AND NEW SANITATION PROJECTS

This post was inspired by the lecture 'Urban poverty, sanitation and social innovation', given by Tatiana Theme on 13.11.19 at UCL. After talking about the problem of slums, and contextualizing WASH and the sanitation ladder, she introduced some examples of toilet technologies lately introduced in Africa that I feel would be worth to explore further. An insight on the characteristics of some of them is then addressed here, encouraging a careful consideration of their respective best applying scenarios and potential evolution. This post is at the same time a way of addressing the possible alternatives that can be adopted to avoid the drawbacks presented by the pit latrine, described in the previous post.

Taking into account all the negative factors associated to the pit latrine, implemented until now as the standard sanitation facility (see previous post), other alternatives need to be regarded. Some new ideas have been lately tested in different African regions in order to fight against these drawbacks and find more suitable facilities:

• Ventilated Improved Pit latrine

It is a pit latrine with the pit slightly offset so that a vent pipe can be fitted in order to exhaust faecal odours. A fly screen is often placed on top in order to avoid bug breeding (Mara et al., 2007).

• PeePoople

As mentioned in previous posts, open defecation is a spreaded practice in the context of bad access to sanitation facilities, its consequences being a feed-back of the problem. The PeePoople case of study, introduced in Nairobi, aims to turn the ‘flying toilet’ into a more ecological, self-sanitised alternative. Excreta is stored in PeePoople biodegradable bags which can be then disposed, and stored for hygienisation and later reuse as fertiliser (Katukiza et al., 2012). The main advantages include that no permanent structures are required; the usage of urea in the bottom of the bags to deactivate pathogens; and an increase of the feeling of safety, especially among women and children, for that they do not have to walk for so long or at night (Reade A., 2016) or deal with extortion of street boys often occupying public toilets (Water and Sanitation Program, World Bank). 

Figure 1. Illustration of the functioning of the PeePoople technology (Sustainable Sanitation and Water Management Toolbox).

However, difficult reception has been caused by the perception of the initiative as a way of marketing an “undignified practice”, and a debate has been reopened. In addition, affordability of the bags, which people need to buy, is another factor causing controversy (Tatiana Theme, 2019).

• Sanergy

Created by a team of MIT engineers, this project features the so-called Fresh Life Toilets, which are franchised to community members to run as businesses. The members collect the waste generated everyday and bring it to a processing site outside Nairobi, where it is converted to organic fertiliser and animal feed. The Fresh Life Toilets seem to solve the main drawbacks of the previously-installed, sewer-connected pour-flush toilets, which include lack of water and water pressure (with the consequent blocking of the toilets), slowness, and high expense (Tull K., 2017).

• Modified pedal-powered Gulper electric pump and eVac

This is an alternative, already implemented in Malawi, which is being regarded as a promising, potential emptying technology. Rubbish in pit latrines is usually a challenge for emptying devices such as vacuum trucks. This method proposes manual pumping instead. Another similar example is eVac, recently developed in South Africa a a portable vacuum pump (Tull K., 2017).

• Iko Toilet

With the Kiswahili word 'iko' meaning 'there is', the 'There is a Toilet' project is a network of pay per use, branded and painted toilet and shower facilities, promoted in Nairobi by architect and founder of Ecotac Ltd, David Kuria (Mwende J., 2012). The initiative tries to end up stigmatisation of toilets being undesirable places to go. It guarantees availability of water and is placed next to sector of commercial activity to facilitate access (Tatiana Theme, 2019). 

The way of operation follows the Build-Operate-Transfer model, which means that, through an agreement with municipal councils, Ecotac bears the cost of construction in exchange of the right to commercially run the facilities during a period of five years (thus ensuring recovery of investment). Afterwards the facilities are eventually to be handed over at no cost to the municipal councils, who can then manage their use (Mwende J., 2012). The Iko Toilet introduces innovations such as the complete 'Dry-Toilet System', a system that features bio-digestion (often linked to methane gas generation) and urine harvesting (which then is sold to companies for production of fertilizer); waterless urinals; low-flush cisterns and water-saving taps (Mwende J., 2012).

Each Iko Toilet facility (there are over 50 already installed) serves an average of 1,000 people per day at a fee of a $10 cents equivalent per use. While discussing on whether it is affordable, an interesting point has been made by Mwende J., 2012, by saying that “$10 cents is much more affordable than what one would use to go to the hospital or purchase some drugs”. In fact, the initiative has profited many people and the demand is high. It not only provides higher hygienic standards and exploration of agricultural and energy production potential uses, but also represents an alternative to the 'filthy' municipal run toilets that are usually feature of pick-pockets and thugs (Mwende J., 2012).

• The EcoSan toilet

This is a toilet facility aimed at the reuse of excreta-born nutrients. It has externally accessible vaults for composting faeces, paper and organic wastes; which then are used as soil conditioner. When it includes sieves for separating faeces from grey matter, the latter is applied in gardens or fields, with or without extra treatment. Sometimes the system includes urine separation, case in which the urine is collected and stored in a tank and later also applied to gardens or fields (Mara et al., 2007). As EcoSan toilets are very different from conventional toilets, careful training has to be given especially to the users, for instance regarding when to close the chambers or when to remove the compost (Tull K., 2017).

• Biogas generator

These are anaerobic digesters which use black water generated in the households (organic wastes, often plus animal excreta) to produce biogas that can be re-invertedly used for in-house cooking or lighting (Mara et al., 2007).

• Pour-Flush toilet

The Pour-Flush toilet is a manually flushed water-seal toilet; similar to the cistern-flush one but with a shallower U-bend so that it can be flushed by manually pouring 2-3 litres of water into the toilet pan (Paterson et al., 2007). It discharges into an adjacent leach pit, which is usually designed so that liquids disperse into the surrounding soil, and solids accumulate and decompose over time, until final removal and use in agriculture (Paterson et al., 2007).

• Septic tank system

It usually includes two compartments, one of which receives domestic wastewater and allows settlement of solids, while the other one carries the anaerobic digestion of that sludge. The effluent can be either directed to soil infiltration, infiltration pits or settled sewerage (Mara et al., 2007).

• Settled sewerage

It receives the effluent of the previously described tanks (whether they are serving one or various households) in order to allow secondary wastewater treatment and water reuse in agriculture. Its hydraulic design is particularly important, and as it does not deal with solids, fundamentally different from the simplified sewerage (Mara et al., 2007).

• Simplified sewerage

The simplified sewerage systems are designed with the same hydraulic principles as the conventional ones, but laxer standards. For example the sewer gradients ensuring self-cleaning are shallower -yet satisfactory; so are the pipe diameters and depths (Paterson et al., 2007); and simple junction boxes are used instead of manholes. The wastewater volume per household assumed in design can be lower, as households have limited water supply; and smaller diameter pipes ease the process of the gradual movement of the solids along the pipes during intermittent flushes. The system of pipes is more flexible, laid inside house blocks or under the pavement instead of the centre of the road; which results in cost savings in excavation, backfill materials and pipe quality (Paterson et al., 2007). 

The main reason for this factors to be slightly different from the general norm is the reduction of cost: typically simplified sewerage represents 20-50% of the cost of the conventional one, and therefore addresses more easily the urgent necessity of informal settlements, where the reliable tiple-tap, in-house water supply required by conventional sewerage is not accessed (Paterson et al., 2007).

Community involvement is an important factor in the implementation, maintenance and operation of simplified sewerage in order to make it sustainable and ease both access and use. 

Conventional sewerage has eventually been categorised as an implicitly 'anti-poor' technology due to its cost and water requirements, and it is important to fight the thought that 'the poor deserve the same standards as provided for the affluent and developed countries' (Paterson et al., 2007), as their physical, social and affordability context is different: as pointed out by many authors, the "one size fits all" does not work in slums. This reminded me of the ‘dual economy’ mentioned by E. F. Schumacher in his book Small is Beautiful, which describes the consequences of, rather than non-applied aids, badly-applied aids, and drives readers to realise that every region suffering a problem would need a “personalized” (and never better, because the factors are often social) solution, which takes into account its peculiarities. In fact, this might be related with the thematic of my previous post "Origin of the African problem" in the sense that conventional sewerage indiscriminately applied as the normed solution often takes its origin in the planning of formal townships in post-apartheid South Africa, that was afterwards automatically extended to other emerging regions. (Paterson et al., 2007).

Figure 2. Algorithm, proposed by Mara et al., 2007, for the selection of sanitation solutions.

As shown by the previous descriptions, in most cases the sanitation alternatives not only enable a cheaper construction and maintenance, but also boost 'waste to value' technology processes (Reade A., 2016). The provided list is, however, just a summary of just a part of the latests projects. Some of them are still under assessment or further study; and in some regions, complementation of more than one method would be a satisfying option. The reader is highly encouraged to take a look at the particular references mentioned in this post in order to know more about each project.