Designers and engineers have long recognized the need for wastewater treatment in developing communities but often are met with the challenges of no piped sewer system, high capital investment, and limited technical skills necessary for operation and maintenance. Enter decentralized wastewater treatment; a solution that treats waste effectively on site and requires no existing piped infrastructure. Decentralized anaerobic treatment systems have existed since the 1800s as septic tanks, but in order to meet the Sustainable Development Goals with a rapidly growing population in the developing world, engineers are attempting to design solutions that are affordable, scalable, more effective, and easier to maintain.
The Engineering for Change Solutions Library features technology reviews of three solutions for decentralized wastewater treatment: Biopipe, the Biofil Digester, and DEWATS.
Biopipe is a decentralized pipe network that treats domestic wastewater for reuse in irrigation and secondary applications (but not for drinking). The system is comprised of a tank, pipe modules, circulation and water pumps, and a UV filter. Bacteria lining the inside of the pipe remove microbiological pathogens, similar to the treatment processes that occur naturally in river beds.
Biopipe is making the transition out of the prototype phase with a recent exclusive distribution deal for Asia and Africa with Metito, a water management design and engineering firm in emerging markets.
The Biofil Digester mimics the natural world with a process similar to the natural decomposition that occurs in soil on a forest floor. Developed in Ghana, the typical digester is housed in a 2’ x 2’ x 6’ concrete structure. Liquid waste rapidly separates from solid as it filters through a layer of permeable pavement. Macro-organisms in the soil below break down pathogens. The digester can be connected to an existing toilet or septic system, is scalable to meet small or large demands, and produces no waste product. The Biofil Digester can be installed above or below ground in a concrete structure with a “microflush” option which conserves the amount of water needed for flushing. Since 2008, more than 4500 Biofil Digesters have been installed across Africa and South Asia.
While the Biopipe and Biofil Digester are manufactured treatment systems, BORDA’s Decentralized Wastewater Treatment System (DEWATS) is a technical design approach to treating wastewater at the household and community level. Founded by the Bremen Overseas Research and Development Association, DEWATS uses physical and biological treatment mechanisms such as sedimentation, floatation, aerobic, and anaerobic treatment to remove pathogens from household wastewater. These treatment stages are commonplace in centralized systems, but what separates the DEWATS design approach is employing a passive system (no power required), low maintenance requirements, and construction from affordable and locally available materials. Hundreds of DEWATS treatment systems have been implemented and are currently operational across Africa, South Asia, and Southeast Asia.
In a recent expansion of our Solutions Library, E4C added these three technologies as examples of decentralized treatment, which has the potential to scale up and meet needs in cities and rural communities. Visitors to this web site know better than most that wastewater treatment is often overlooked in discussions about global development. With these new additions and more sanitation technology planned for the future, we hope to draw attention to the options available to those in need.