Perfector – R: Avanced water treatment technology for developing countries04/03/2015
Economic growth does not always bring with it immediate sanitary improvements and waterborne illnesses are still far too common. Not only that, but traditional wastewater treatment facilities have high operational costs and are big users of energy.
In spite of the impressive growth by former third world countries such as India, problems posed by waterborne pathogens still cause about 80% of illnesses. A huge part of this effort is the development of wastewater treatment facilities. Long bedeviled by poor access to the energy needed to operate wastewater treatment systems, only 20% of communities in India had access to wastewater treatment in the past.
Now, a new technology developed by Aquanos Energy Ltd, and further enhanced by World Water Works, is now available and promises to produce a high quality effluent at a fraction of the total energy consumption of conventional wastewater treatment plants.
The new technology captures and harnesses the symbiotic relationship between bacteria and algae. This natural process results in a 90% reduction in plant energy, reduces a wastewater treatment system’s operational costs by 40-60%, and reduces capital expenditures. Its manufacturers claim that it is far more sustainable than other biological wastewater treatment systems that use microorganisms to treat wastewater, so it is ideal for use in India and other energy-constrained countries.
The process has been proven in a demonstration project and is now being launched to the municipal market in India and Africa. Further enhancements are already on the horizon, including an enhanced nutrients removal system and resource harvesting of the algae for use as a fertilizer and other useful products.
Biological wastewater treatment
In most conventional intensive wastewater treatment operations, organic material and nitrogenous compounds are degraded by aerobic microorganisms (bacteria), which require large amounts of oxygen for their biochemical activity. Supplying this oxygen usually requires mechanical devices, like surface aerators and air compressors and blowers to introduce air into the reactors. These devices use huge amounts of electrical power. About 60% of the energy consumed by treating water comes from blowing oxygen into the wastewater. The associated power costs impose a significant (sometimes insurmountable) financial burden on communities, making wastewater treatment effectively impossible for many communities in India and Africa.
Several years ago, engineers at Aquanos began looking for a better, more sustainable method, and one that would extend the benefits of advanced wastewater treatment to countries that lacked affordable energy alternatives. They noted that water is the single largest factor in world energy consumption, including water treatment, supply, purification, and wastewater. It is also the major cause of disease in these countries, and they knew it was possible to solve that problem. But perhaps most importantly, they wanted to find a way to change the way wastewater is viewed. Rather than thinking of wastewater as simply dirty water, the Aquanos team saw wastewater as a resource from which nutrients could be derived or converted to energy and products.
Recognizing that eliminating the need to blow air into the wastewater would significantly reduce energy needs, they examined a few alternatives, eventually alighting on the plan to use algae, an aquatic plant that consumes CO2 from water and produces oxygen. Bacteria supplies carbon dioxide to the algae, algae provides oxygen to the bacteria, and both remove impurities from wastewater.
Production of oxygen by algae is not a new idea – it has been used extensively in wastewater treatment, either in conventional waste stabilization ponds or the more engineered high-rate algae ponds. However, these lagoon-based algae wastewater treatment systems require large areas of land because the algae ponds have to be very shallow so they receive enough sunlight. Such systems are also not highly-controllable systems, resulting in inconsistent effluent quality.
Mixing the oxygen-producing algae with the oxygen-consuming bacteria in a single environment turns out to create conditions that are not optimal for either type of organism. For example, the presence of large numbers of microorganisms creates high turbidity, which turns water brown, thus obscuring the sunlight the algae need to grow. Because of these issues, many systems that started out using algae to produce oxygen had moved into forced aeration – with its high energy use.
Spreading the word
Algae need sunlight to grow, so the system Aquanos developed is most applicable to sunny and warm climates. Plans are now underway to launch the Aquanos system to the municipal market in India and Africa, offering it as a way to deliver wastewater treatment to urban and suburban communities that have very little energy. Technology that would clean up wastewater, not use much energy, and produce a fertilizer that can be used locally, is a powerful concept.
Compared to other activated sludge and highly energy intensive processes, which leave you with wastes that have to be hauled, this low cost sustainable technology has the potential to rapidly increase the population of India that has wastewater treatment from its existing 20% to much closer to the US’s rate of 90%.
In addition, Aquanos and World Water Works are currently working on broadening the patent with process trains and optimized treatment to generate a monoculture, harvesting fertilizer, animal feed, bioplastics, and biofuels. The algae consume nitrogen and phosphorous from water – and these are expensive commodities. The team’s ultimate vision is to obtain wastewater from one side of the process and biofuel from the other side, along with clean water.
The new process has two distinct layers of benefits. The first is that it is truly a cost efficient technology that reduces capital expenditures and energy/operational expenditures, while producing high quality effluent. The second is its ability to facilitate harvesting resources, in the form of biogas and other high value products.
In the long run, the development of a much cheaper wastewater stream that includes the sale of harvested resources will be a game changer. Instead of simply spending money on wastewater, people can make a profit from it – making the Aquanos system a truly revolutionary approach.