Optimising decentralised low-cost wastewater infrastructure by managing the microbes

Here we argue that decentralised and point of use water infrastructure and technologies are fundamental in delivering health and economic sustainability in rapidly growing cities of the Global South. Further we advocate that research on decentralisation with developing world partners has the potential to catalyse radical change in unsustainable centralised western practices and thus will be mutually beneficial. There has been significant investment by charities and government agencies in developing novel wastewater treatment technologies and many are now close to market readiness. The Asian Institute of Technology in Thailand are piloting a suite of novel market-driven decentralised biological wastewater treatment technologies that were developed with Bill & Melinda Gates Foundation funding. The technologies work but their performance is variable. There is evidence that this is caused by variability in the microbial populations at the heart of the technologies, which are poorly understood. We will work with AIT to characterise and optimise the structure and function of the microbial treatment communities. The aim will be to mitigate the risk of failure by refining the AIT designs and offering rapid low-tech remediation strategies that can be deployed by customers should failures occur.

To understand the benefits one must be aware of the nature of the problem. There have been significant improvements in the sanitation provision for the urban population in Asia over the last 20 years. In Thailand, 95% of people living in cities have access to some form of improved sanitation. However, whilst there are now 101 municipal wastewater treatment plants across the country, they serve only 1% of the total 7,775 municipalities. The vast majority of households have on-site sanitation in the form of crude cesspits or conventional septic tanks. In only 6% of cases does the effluent from these enter a networked sewer system and even then 90% of that sewage is disposed of unsafely. Thus the on-site sanitation primarily serves to settle out the sludge, which is intermittently collected and often dumped unsafely, and the effluent either soaks away into groundwater or is discharged directly into open watercourses. All of the circumstantial evidence points to this having an enormous effect on public health. Thailand's Ministry of public health figures show that morbidity from diarrhoea has doubled in the last 2 decades; mortality has diminished but primarily because of improvements in primary healthcare. So inadequate onsite sanitation is a problem, but the cost of providing sewerage and centralised wastewater treatment to 94% of the population is prohibitive. If we are to improve public health in Thailand, and beyond to the countries with poorer provision in Asia, then there is no alternative but to improve decentralised sanitation.

Improving sanitation will directly address the social and economic burdens of ill health. Episodes of diarrhoea can lead to loss of income, failure to attend school and increased expenditure on medicine. It has been estimated that a single episode of diarrhoea for one person can cost a family $6.61. Although the benefits are clear, successfully rolling out sanitation solutions has remained problematic. It is expensive for the state and successful business models for both small enterprise and big business are rare. AIT, in partnership with the Bill and Melinda Gates foundation have taken a market-based approach, seeking impact through sustainable, viable businesses targeting key market segments. The cess-to-fit and Solar septic tank innovated at AIT are designed to address key unmet needs within these segments and thus provide a competitive advantage in the market. They are therefore critical components for business success and impact delivery. Any loss of confidence in the technologies renders their whole model vulnerable. This is where the collaboration with Glasgow will help by improving their performance, making them more robust, and providing a better service to the customer. This will enhance the business proposition. Furthermore, by trialling the technologies in Scotland it opens the prospect of export from the Thailand to the Northern Europe; where there is a significant market for cheap and reliable decentralised water technologies

We have engaged water professionals and regulators as an advisory committee to guide the delivery of our program in a series of in-person team meetings to engage and critically reflect on progress towards our project milestones and to ensure our work is successful in breaking down the barriers to innovation in wastewater treatment