Editor’s pickReclaiming water

12-02-2018

Although 80 per cent of wastewater around the world is discharged back into waterways without being treated first, regulatory compliance, water shortages, and pollution are all spurring innovative and sustainable technologies for industrial wastewater treatment.

 

By Nalin Amunugama, General Manager BOGE KOMPRESSOREN, Asia Pacific. Image Credit: BOGE

 

Graphene-based membranes are extremely light and strong, making them of interest in real-world applications like desalination. Image credit: Jynto, Wikimedia Commons

 

More than a vital component of ecosystem and human health, safe and clean water form the core of sustainable development. Yet, the reality is that 80 per cent of wastewater is released into the environment globally without being treated or reused.

Exacerbating this problem is the lack of infrastructure and resources in most cities to address wastewater management in an efficient way. Vietnam, Myanmar, Cambodia, and Laos are among some of the countries reporting the lowest percentages of wastewater treatment in the Southeast Asia region.  

When properly managed, however, wastewater can be a great source of water, energy and other useful materials. Given wastewater’s environmental and economic benefits – be it in meeting growing water demand, improving energy production or supporting sustainable industrial development – governments and corporations are stepping up efforts to enhance its collection, treatment and reuse.

Singapore is heeding this call, and the nation has pledged to pump some US$200 million into a water industry that is expected to add about US$2.8 billion to the country’s economy by 2020.

Similar investments have also resulted in innovative technologies that are disrupting the water sector and making an impact by maximising efficiencies and optimising consumption.

Membrane technologies such as reverse osmosis and microfiltration, as well as biological treatments are among advances that are currently being tested in labs and increasingly finding applications in wastewater processes. In plant facilities, technological upgrades, as well as operational modifications are helping to improve water use and recovery.

“Adopting smarter approaches to water management will become the norm as urban demand and uses of water evolve,” Nalin Amunugama, General Manager of BOGE Asia Pacific, a leading supplier of industrial air compressor systems, said. “Leveraging new technologies will not only help industries and cities better exploit wastewater’s potential, but will set a precedent for how this valuable resource is managed in the future.”

 

Synchronous reluctance motors offer high energy efficiency, low-bearing temperatures and longer life spans. Image credit: ABB


Optimising energy efficiency

Where wastewater is concerned, the biggest contributors cannot be easily overlooked. Industry, for example, is responsible for 22 per cent of global water use, but remains a major polluter as it treats only a proportion of wastewater before discharging it.

As more sustainable agendas are brought to the fore, companies are reviewing plant operations to achieve less pollution and bigger savings, through the energy-efficient implementation of systems like fans, motors and pumps.

A major step forward in both sustainable electric motor technology and the water sector is the use of the synchronous reluctance motors (SynRMs), which offer the energy efficiency of permanent magnet motors and the maintenance simplicity of induction motors.

The system operates at a high level of efficiency in full and partial load and offers greater power reserves, allowing businesses to lower energy consumption and costs. Less heat is also dissipated from the SynRM motor and it runs much cooler and more quietly as compared to traditional induction motors.

Already, the low-energy motors are being used by water company, Evides Waterbedrijf in its new water pumping station based near the small village of Niuewdorp in the Netherlands. The station deploys three 250kW motors that pump water from three reservoirs with an estimated capacity of 12,000m3 of purified water.

As SynRM rotors can be constructed entirely from high-strength, low-cost materials, the technology’s broader application in Asian markets is expected to grow, due to its high-impact but low-cost investments. The motor is increasingly favoured for its longer life span and minimal maintenance requirements, making the technology extremely useful when implemented in inaccessible or more remote areas where regular system checks may be difficult. The application of SynRMs in water facilities in such areas will be a big help to communities in managing their water resources more efficiently.   

 

BOGE’s condensate cleaner: (1) Hoses and connection nipples direct the condensate into a pressure relief chamber, (2) from which the condensate flows to the first-stage filtration element, polypropylene. (3) The pre-cleaned condensate then moves to the second-stage filtration element, high quality active carbon. (4) The cleaned condensate, free from synthetic coolant and mineral oil residues, is finally discharged into the sewage system. Image credit: BOGE

 

Condensate separation technology

The high incidence of untreated industrial wastewater has also prompted cities to introduce various wastewater-focused regulations

 In 2015, Vietnam passed a law that necessitated wastewater treatment and management for the first time, while in Singapore, most industries pre-treat wastewater before releasing it into the combined sewer system, in line with the strict requirements of the Environmental Protection and Management (Trade Effluent) Regulations.

Oily wastewater, especially, is a major industrial concern as it is capable of high levels of contamination. Efficient oil separators have thus become crucial to ensuring wastewater effluent meets legislation standards.

In manufacturing plants, compressed air condensate, a source of oil-contaminated moisture, has to be treated before being released into a foul water network. In the case of a simple suspension, oil or emulsions can be separated from water by superior condensate separation technology.

“Condensate, if not treated, can be collected into drums or storage tanks and disposed of in an approved facility. But this can result in significant operating costs,” Mr Amunugama cautioned.

To address this problem, BOGE developed a cost-effective system that utilises high quality active carbon and polypropylene filter elements to provide optimum condensate cleaning.

These condensate cleaners are compatible with all types of oils and lubricants, and can be adapted to different compressor stations. Servicing the systems is also fuss-free as the disposal of filter elements can be directly removed from the unit and replaced easily, without the additional step of removing liquid oil residues from containers. One outcome is the reduction of both maintenance and environmental disposal costs.

The operating principle is simple enough – oil-contaminated condensate is first directed into a pressure relief chamber and later flows to the polypropylene (a specially manufactured plastic fibre), where it undergoes filtration. The pre-cleaned condensate is then filtered a second time using high quality carbon element.

Once the mineral oil and synthetic coolant residues are removed, the treated condensate is directly discharged into the sewage system. This double filtration process using two powerful filter elements has multiple advantages, including the elimination of liquid oil residues, extended filter replacement intervals, and versatility in application.

With a typical cartridge lifetime of six months or 3000 hours, BOGE’s oil/water separator guarantees condensate treatment that is both reliable and efficient.

Commercial businesses dealing with the risk of oil emissions into water supplies or sewage networks, in particular, will benefit from the innovative technology, as they look to meet a variety of environmental regulations and simultaneously reduce total waste disposal costs.

 

Affordable water desalination

Apart from offering sustainable solutions, technological advances are also focusing on making water treatment and management more accessible to industries and communities.

This can be observed in traditionally expensive and energy-intensive processes like desalination, which is too often considered a less-than-viable practice in many water-deprived regions that also have to deal with energy shortages.

A breakthrough innovation – in the form of a special filter material – seeks to reduce the time and energy required to produce clean water through reverse osmosis. Developed by Lockheed Martin, the graphene filter, known as Perforene, is 1,000 times stronger than steel and can withstand higher temperatures and pressure as compared to current filters that use plastic polymers.

With a thickness of just one atom, the Perforene membrane uses less energy to drag water through while trapping salt and other impurities – potentially capable of lowering the energy cost of conventional reverse osmosis desalination by up to 20 percent.

This molecular filtration may just be the solution to the oil and gas sector, which generates 18 billion gallons of wastewater annually. Areas with insufficient supplies of freshwater but lacking the finances will also benefit from the technology.

 

A wealth of opportunities

In many developing countries, as it is in some parts of SEA, the release of untreated water remains common practice, primarily due to inadequate infrastructure, and technical and institutional capacity.

However, vast opportunities are to be had with the increased application of innovations designed to make wastewater treatment less expensive, more accessible and sustainable.

Studies in the region have also shown that revenues from wastewater by-products are considerably higher than the operational costs of wastewater systems that harvest these by-products, indicating that resource recovery from wastewater can be a lucrative business model.

Consequently, more needs to be done across the region to support municipal and local governments in managing wastewater and optimising its resource benefits.