Water Recycling and Reuse
Recycling and reuse augurs well for the environment as well as for industries. By setting up reuse and recycling systems, the limited freshwater supply can be better prioritised. With focus on municipal industrial tie ups, cash-strapped municipalities will stand to gain from reuse by means of water purchase agreements.
WABAG’s offerings are based on the conviction that “Water is too precious to be used just once”. The company has numerous standout references that employ advanced multi barrier systems and testify to its expertise in the domain of water reuse.
Testifying to WABAG’s pivotal position in the context of water reuse is the plant executed by WABAG at Windhoek, Namibia in 2002. The capacity of the reclamation plant totals 21,000 3/d and the raw water used consists of treated municipal wastewater. The key process steps are: Oxidation and Pre-ozonation, Powdered Activated Carbon Dosing, Coagulation and Flocculation, Dissolved Air Flotation (DAF), Dual Media Filtration, Main Ozonation, Biological Activated Carbon Filtration (BAC), Ultrafiltration, Disinfection and Stabilisation. Since start-up, all the relevant standards have been fulfilled without difficulty for over 15 years in operation.
The company’s recycling capabilities are highly pronounced in the industrial sector too. In India alone, WABAG has about 20 industrial water recycle-and-reuse projects to its credit. The water reclamation plants for Oil & Gas majors like Indian Oil Corporation and Reliance Industries are marquee references in this regard.
Energy Neutral WWTPs
Urban local bodies in emerging economies are not cash rich. To ensure maximum returns on investment in wastewater treatment and increased life of a project, a scientific approach is required for the biological treatment process. This is where “power-neutral” STPs pave the way forward. Sustainability of the treatment process is crucial and it dependent upon constant and assured supply of power.
Green power production from sludge biogas has numerous advantages. First, it not only ensures the plant is self-sustaining but also helps earn carbon credits, a source of revenue. Second, the burden of operating expenditure for the client is substantially reduced by installing a gas engine, which has an attractive payback period of three to four years. Third, the digested sludge is high in organic content and can act as a natural fertilizer high in N, P, K (nitrogen, phosphorus and potassium).
There are time-tested cases proving the viability of power-neutral STPs. Large scale power-neutral installations are present in Xiaohongmen, China, and in Turkey for 600,000 m3/day and 400,000 m3/day WWTP. In India, in 2004, WABAG was entrusted with the turnkey realisation of a new biological sewage treatment plant at Kodungaiyur, Chennai, India. After commissioning in 2006, WABAG also assumed responsibility for operations and maintenance of the plant for a period of 10 years. It is the largest plant of its kind in India – achieving 98% self-sufficiency in terms of power consumption.
Biological Nutrient Removal
In connection with global discharge requirements, one of the major changes is the shift to nutrient removal (nitrogen and phosphorus) to avert eutrophication. A traditional approach for nutrient removal will mean a doubling of the existing energy used to treat wastewater and a reduction in the potential gas production from the digestion of biological sludge.
About two decades ago, a “new” cacteria named Anammox was discovered that is able to transfer nitrogen from ammonia and nitrite to free nitrogen following a completely different pathway. When following this pathway, the following advantages compared to nitrification-denitrification can be gained:
a. 63% reduction in oxygen demand (electrical power) and nearly 100% reduction in carbon demand
b. 80% reduction in sludge production
Since Anammox was discovered, WABAG has worked together with the Suisse Federal Research institute (EAWAG) to develop a new technology that is able to best possible profit from this bacteria. Having tested different technology approaches like Sequencing Batch Reactors and Aerobic Granules, the solution provides the best process stability. Fixation of the Anammox bacteria on WABAG’s proprietary FLUOPUR MBBR media provides a new technology for deammonification — DAMOPUR.
DAMOPUR has now been successfully implemented in two wastewater treatment plants (WWTPs) in Switzerland.
Removal of Micro-pollutants
The discussions regarding micro-pollutants, which are substances that occur in very low concentrations (ng/l to μg/l) in water, first commenced around 2000. Owing to increasing industrialisation, population density and medication use, a growing number of micropollutants such as hormoneactive (endocrine) and pharmaceutical substances, chemicals and pesticides are entering our eco-systems. Such micropollutants are found not only in municipal wastewater but even in groundwater at some places.
While to date, treatment plants were focused mainly on the elimination of nutrients (carbon, nitrogen and phosphorus), their barriers against organic micropollutants were insufficient. Proven technologies are already available that can be used to great effect in this area, comprising oxidative, adsorptive and physical processes. WABAG possesses expertise in all of these areas.
For more than a decade, WABAG has been involved in R&D aimed at the elimination of micropollutants. Numerous research projects have been implemented, for example, in cooperation with the Swiss Federal Environmental Protection Office, the Swiss aquatic research institute, Eawag, and the Vienna University of Technology in Austria. WABAG’s patented technologies for elimination of micropollutants comprise:
Ozonation: BIOZONE®
Adsorption: PACOPUR®,CARBOPUR®
In 2013, the first BIOZONE® customer plant went into operation in St. Pourçain-sur-Sioule, France, and since then WABAG has received contracts in Reinach, Thunersee, Altenrhein and Porrentruy in Switzerland.