Reducing energy consumption by 8,000 kWh and being able to generate 15,000 kWh of electrical power per day can save 500,000 euros operating costs in a year, as a project carried out by WEHRLE Umwelt GmbH on behalf of a pharmaceutical company found. WEHRLE Umwelt has been working with environmental technologies for over 30 years, principally focussing on plants for industrial wastewater treatment. The company offers intelligent solutions that are far removed from conventional wastewater treatment plants.
Companies in the wastewater treatment sector are usually only contacted when wastewater pollutants exceed regulatory limits. “Many companies still believe that wastewater treatment plants generate costs and very little else. Nobody spends money on environmental technologies in order to save the planet. Or put another way, companies only set up wastewater treatment plants when they conclude that not installing them will be more expensive than installing them,” said Dr. Bernd Fitzke, head of WEHRLE Umwelt’s product development division. Not installing wastewater treatment plants might in fact become more expensive than installing them due to charges and fines applied because highly polluted water has been introduced into public sewage plants or because legal regulations have not been complied with.
This is basically the only reason why companies are likely to invest in a modern wastewater treatment plant. However, they might be more inclined to do so if they realized that a wastewater treatment plant could be a profitable investment. Companies need to be made aware of the fact that purified wastewater will then become a resource, i.e. that wastewater treatment leads to less wastewater as well as saving fresh water.
A wastewater treatment plant can be a profitable investment for a laundry, for example. Most types of wastewater contain energy in the form of heat, which can be re-used. In the case of laundries, the advantage of treating wastewater is that the process produces water that is softer than fresh water, which, when returned to the washing cycle, reduces costs that would otherwise arise from the water softening system. Thus for laundries, the installation of a wastewater treatment plant has four advantages: reduced fresh water consumption, lower water softening costs, reduced quantities of wastewater and lower energy consumption. Taking these aspects into account alongside company-specific conditions, the installation of a wastewater treatment plant pays off within a relatively short timescale.
“We are specifically looking for projects where WEHRLE Umwelt can put its long-standing experience in wastewater treatment to good use,” says Fitzke. “If a system is seen as profitable from an economic point of view and does not need to be purchased because of changes in legislation, there is a strong sales case for the installation of wastewater treatment plants,” explains Fitzke. The economic argument is becoming increasingly compelling – including for companies in the pharmaceutical sector that need to tackle wastewater treatment.
One of WEHRLE Umwelt’s recent projects involved the complete revision of the wastewater management system of a client in the pharmaceutical industry. The company used process water and wastewater in its wastewater treatment plant, with the result that the plant had to cope with solvents, production residues and a large quantity of organic solids and reached saturation point. The company hoped to be able to solve the problem by simply constructing a bigger wastewater treatment plant.
WEHRLE Umwelt suggested a different, economically more viable option, which also had the potential to reduce the pressure on the environment: “The treatment of wastewater must be a rational process if the aim is to improve discharge values and, if possible, also generate added value,” explains Fitzke.
WEHRLE Umwelt started its investigations by studying individual wastewater streams for the presence of critical pollutants and by sorting them by pollutant load in order to treat them separately.
The company found that individual wastewater streams contained large quantities of organic material. Removing the organic fraction and converting the resultant energy into electrical power and heat in a biogas production plant has a considerable effect on the overall energy consumption of the wastewater treatment process. Energy is produced and energy consumption is reduced in the clarifying stage, normally an energy-intensive process, but for which the amount of energy required for wastewater treatment is reduced by removing the organic load.
WEHRLE Umwelt changed process control and installed a biogas production plant in the wastewater streams with the highest organic load and managed to reduce the polluting load to around one third. This in turn decreased the chemical oxygen demand* in the treated effluent of the existing wastewater treatment plant to one fifth of its original value. In addition, the chemical demand of the existing treatment plant was reduced by 30 to 50 percent.
The biogas plant provides the downstream block heat and power plant with a daily quantity of around 8,600 m3 biogas. With an electrical efficiency of 30 to 40 percent, this amount corresponds to between 15,000 to 20,000 kWh electricity per day – which is the energy consumed by around 2,000 households a day. In addition, the block heat and power plant produces heat energy of around 20,000 kWh per day, which can be used for processes that require heat. This example clearly shows that wastewater treatment isn’t just a cost, but can also be beneficial to users and the environment.
* Chemical oxygen demand (COD): amount of oxygen a wastewater treatment plant consumes when making existing organic biomass accessible to microbial digestion. It is an indirect measure of the quantity of organic compounds in water.
Further information:WEHRLE Umwelt GmbHBismarckstr. 1-11D-79312 EmmendingenE-mail: fitzke(at)wehrle-umwelt.com