Wastewater treatment has become an increasingly critical component of manufacturing operations.
Whether you are in the metalworking, foundry, surface treatment or wire and tube industries, along with many other industries, you will need water during some stage of your manufacturing process. However, rising water, energy and waste management costs continue to increase and this affects the overall operating costs of your business.
Regulations are becoming more stringent
With increasing pressure from government departments and the introduction of new environmental laws, companies must remain compliant with tightening wastewater treatment, handling and disposal regulations. The introduction of acts and laws that cover clean water, resource conservation and recovery and safe drinking water by local municipalities are now being enforced with vigour. Companies must take note and introduce water reuse and recycling systems into their manufacturing operations so as to adhere to these laws and acts rather than allowing it to become an easy revenue stream for these state and local departments to administer fines and penalties.
“These issues have caused manufacturers to consider more affordable, yet effective, alternatives for water reuse and recycling. For example, machine shops are looking more closely at the efficiency of the equipment they use to deal with oily wastewater created by tramp oils in coolant sumps as well as vibratory equipment, floor scrubbers and so on,” says Brandon Mew, Director of Water Solutions & Innovations.
Locally manufactured evaporator units
“Recognising this, Water Solutions & Innovations has designed and manufactured a range of evaporator units for the South African market.”
“We teamed up with Chemical Engineer Freddie van der Merwe and Dr Eric Hoffman so that we could develop a cost-effective water recycling system. Most engineering companies in South Africa operate equipment that needs some form of coolant when machining, shaping or cutting the various metals such as aluminium, iron, steel, copper and other non-ferrous metals.”
“Most companies processing these materials will face the problem of how to dispose of coolant contaminated with oil. This coolant has to be packaged, labeled and sent to a proper hazardous waste disposal site at an extreme cost to the company.”
“When you consider that machine coolant is approximately 95 per cent water, they are paying to dispose of water that in essence can be very effectively recycled for the company’s own reuse. Hence we decided on the evaporator technology. Although not a new technology, the cost of importing the equipment to manage the coolant and water waste stream has become exorbitant and we felt we could manufacture a machine locally.”
“Evaporation is a natural phenomenon recognised as a clean separation technology in the treatment of wastewater. Traditional atmospheric evaporators using direct heating methods are inefficient and expensive to operate. Conversely, our evaporators create a vacuum to lower the boiling point of the water. This is a more efficient way to evaporate the wastewater, thus lowering the system’s operating costs. Also, no emissions are discharged into the atmosphere because it is a closed-loop system,” explained Mew.
Technology
“The evaporator utilises the process of vacuum induced evaporation (VIE), which as I said previously, lowers the fluid boiling temperature (boiling point) thereby allowing the vapour pressure to overcome atmospheric pressure and start the boiling process,” said Dr Eric Hoffman, Managing Director of Chemical Solutions & Innovations.
“Mechanical vapour recompression (MVR) is used to superheat vapour generated in the boiler. The superheated vapour is conveyed through a specialised vacuum pump to a condenser which recaptures the latent heat of the vapour and transfers the energy back to the boiler, thereby making this form of wastewater treatment highly cost effective.”
Process description
“Waste is fed from the main waste holding facility into the evaporator unit. A pre-filtration unit is optional. The liquid is heated to 88°C with electrical resistors in a boiler vessel and then a vacuum pump is activated to induce boiling conditions. Steam is then extracted from the boiling chamber and condensed in the main heat exchanger. A forced circulation loop recovers the energy back to the boiling chamber. Electrical resistors will remain off once optimum energy recovery is achieved and this causes the system to run off its internal energy and the only power consumed by the process is through the pumps. This operation allows the unit to treat basically any liquid waste at a very low operational cost of 0.1kW/L.”
“The benefit of using evaporator technology to treat liquid waste is that it reduces the actual liquid waste to 10% of initial volume. This results in a large reduction in waste removal costs and environmental impact by 90%. Additionally the company can reuse the distillate in the plant for certain processes.”
“The unit sizes that we are manufacturing offer recovery rates from 100 to 700 litres per hour. However, larger units can be custom made upon customer request. The actual physical size of the smaller units is 1 200 x 2 400 x 2 100mm and the larger units are 1 500 x 3 000 x 2 100mm.”
“They are fully PLC controlled and only require minor maintenance procedures. Optional extras offered are a pre-oil skimmer to remove all surface oil from incoming liquid waste, a pH correction option to neutralise incoming waste to protect and extend equipment life, a post skimmer that removes all floating organics in the distillate and an auto cleaning option that will automatically chemical flush to reduce maintenance.”
“Executives of manufacturing entities should be concerned about wastewater treatment for many reasons, and the best way to turn genuine concern into effective solutions starts with an awareness of current options for wastewater treatment equipment.”
“Reasons such as improving a company’s working environment, employee morale and public image, as well as adhering to ISO initiatives, should be a standard operational procedure these days. By prioritising environmental awareness these efforts will promote a ‘green’ operation.”
“There is the bottom line issue as well. Companies should care about wastewater treatment and reuse because it enables them to cut operational costs and increase profitability. The goal should be to recycle coolant, wash water and other fluids internally to increase tool life, improve product quality, reduce maintenance and prolong the usage of working fluids. When the time comes to finally dispose of the fluids, companies have a smaller volume to get rid of, or a concentrated stream they can treat themselves for lower-cost handling.”
“In today’s world, there are many available options that make it possible for companies to do the right thing with their wastewater, both environmentally and from a business perspective,” concluded Mews.
For further details contact Chemical Solutions & Innovations on TEL: 011 392 2090 or visit www.csi-africa.co.za
