Making Every Drop Count: Recycling Municipal and Industrial Wastewater for a Sustainable Future

In recent years, limited water resources combined with the growing demand for freshwater, rapidly changing weather patterns and environmental concerns have spearheaded water reuse as a leading solution in the battle to secure water resilience.

What is Water Reuse? Also known as water recycling or reclaimed water, water reuse captures wastewater, stormwater, saltwater or graywater and treats it as needed for domestic consumption, industrial processes, surface or groundwater replenishment and watershed restoration. The term municipal wastewater reuse commonly relates to tertiary treatment followed by desalination and advanced oxidation (typical process, there are variations), which produces high quality potable water from wastewater at a fraction of the cost, compared to seawater desalination.

Across the globe, more and more communities and businesses are investing in water reuse to ensure residents have safe drinking water supplies, industries can utilize water to enable the ongoing operation, and farmers have water to grow food. Wastewater reuse also ensures our environment is protected and our economic future remains secure.

. Water reuse is a proven method to improve water resilience by supporting a broader water portfolio. In recent years, a growing number of countries, including India, are incorporating water reuse into their water management strategies to ensure a drought-proof, safe, reliable, locally-controlled water supply.

According to a recent survey by Bluefield Research, the Reuse market stands at $22 billion and will grow 27 percent by 2027. India is the biggest consumer in the world of freshwater, accounting for roughly 750 billion meters annually, according to the World Bank – yet just 30 percent of its wastewater is recycled. As population growth, drought and other climate-change related events continue to hamper India’s water supply, there’s a huge opportunity for the country to rely on municipal and industrial wastewater reuse as a solution to its growing water crisis.

By 2030, if India could increase the percentage of urban wastewater it recycles to 80 percent, there would be an increase of 400 percent in the volume of available wastewater to reclaim and directly reuse. Fortunately, more and more applications in the industrial and agricultural sectors are relying on wastewater reuse, but the municipal sector is still lagging a bit behind.

. Water Reuse in Singapore and Neighboring Countries An example of a nation who leads the pack in wastewater reuse is Singapore. Singapore’s successfully executed water supply initiative called “Four National Taps” has set an impressive precedent for its neighboring nations to follow. Its robust and diversified water supply system is based on four “water pillars:” high-grade reused water - also called NEWater, local catchment (i.e. rain and stormwater reservoirs), imported water (primarily from Malaysia) and lastly, desalinated water.

This integrated water management approach maximizes each source's efficiency, addresses the local industries' water-intensive needs, and serves the growing awareness towards global issues such as climate change, increasing droughts, expanding urbanization and the rising cost of energy.

. IPR or DPR? One of the most significant contributors to the changing views on water reuse in recent years is the recognition of its importance by entities such as the United Nations. The 2017 World Water Development Report, for example, focused on wastewater as a safe and sustainable water resource, while more successful case studies of water reuse have expanded its frontier from agricultural irrigation and limited urban uses to a variety of applications, including potable reuse.

. What are IPR and DPR and what is the difference between them?

Two potable water reuse options currently gain prevalence: Direct Potable Reuse (DPR) and Indirect Potable Reuse (IPR). In IPR, treated wastewater is released into groundwater or surface water sources and joins the natural water body. This water is later reclaimed and treated to meet potable water standards just like natural water in the aquifer. In DPR, purified water created from treated wastewater is introduced directly into a municipal water supply system without an environmental “buffer” of any kind. Instead, an engineered buffer (i.e. tanks that provide limited residence time) may be used.

After decades of IPR applications, a combination of improved effluent water quality, advanced treatment and control technologies and increasing demand for water supplies has finally sparked the interest in DPR. In India, Bengaluru, the fastest-growing Indian city behind New Delhi, has now considered both IPR and DPR to combat the water crisis catalyzed by population growth and climate change.

. Historically, the retention time of the water stored in an environmental buffer was thought to help correct any issues if any water impurities were found. Since IPR was first applied decades ago, DPR technologies have advanced such that the need for an environmental buffer has been eliminated. Some believe that when water undergoes advanced treatment, directing this water into a groundwater aquifer or surface reservoir may not improve water quality and result in the exposure of high-quality water to potential environmental contaminants. Nonetheless, regulatory agencies still must be convinced that DPR is, in fact, a safe and reliable water supply option.

Because of that, despite a noticeable trend and an overall readiness to employ more reuse applications, many countries remain behind countries such as Singapore when it comes to widespread DPR deployment. This is mainly due to tighter regulation as well as an overall public concern regarding the potential health hazards of DPR when not performed with meticulous care. However, as more and more DPR pilot projects will prove that the process is reliable and safe, it may eventually become an accepted solution by different agencies.

While the likelihood of reclaimed water to cause a major disease outbreak remains extremely low, the potential transmission of infectious disease by pathogenic organisms, or the release of organic contaminants, remains the principal public concern regarding DPR. This concern, however, is fairly ungrounded in developed countries, where dozens of tightly regulated DPR facilities produce high-quality potable water while adhering to the strictest health standards.

. Wastewater Reuse for Industrial Applications The main industrial sectors that utilize wastewater reuse are power plants, food & beverage industries, chemical manufacturing, hydraulic fracking, oil & gas and petrochemicals. What are the main factors driving the need for more efficient industrial water reuse technologies?

In most cases, water scarcity increased awareness of Corporate Social Responsibility (CSR), and the need to reduce costs by maximizing water recovery plays a significant role. Some industries, however, are still hesitant to adopt reuse solutions on a broader scale.

. Electricity utilities are challenged by a competitive use of water in water-scarce regions, and therefore need to rely on alternative water sources. Water use applications in electricity utilities include cooling tower make-up, boiler feed, environmental control, sanitation, irrigation of landscape and environmental stewardship. The day-to-day operation of a thermoelectric power plant, for example, is especially water-intensive and requires a large quantity of fresh water to sustain its ongoing activities.

To address this pressing need for water in such large-scale quantities without exhausting fresh water supplies or competing with municipalities over local water resources, reused municipal wastewater can offer a feasible alternative water supply for the power sector.

. The power sector is constantly considering degraded or non-traditional water supplies to offset water consumption. However, although reclaimed wastewater seems to be an obvious choice due to its easy accessibility and unlimited availability, few power plants currently use municipal reclaimed water.

Industrial facilities owners typically think of water management issues in their facility in two ways:

Securing water supplies for operations, including supply and discharge

Complying with quality standards for wastewater discharge

On the one hand, putting in place a smart reuse management plan helps facilities:

Reduce their freshwater demand

Bring down generated wastewater volume

Minimize subsequent discharge permits

Bring down the costs of freshwater acquisition and effluent treatment

In some cases, provide recycling opportunities for certain industrial by-products

. On the flip side, adequately managed reuse requires knowledge, financial investment and, understandably, modification of current operations for both DPR and IPR applications. Weighing the pros against the cons, implementing a reuse management plan often proves to be the most sustainable, resource-efficient, cost-effective and environmentally oriented alternative.

Evolving regulation that supports more rapid reuse market growth and encouragement at the legislative level is also a key factor contributing to market readiness. Therefore, all predictions indicate a much broader adoption of water reuse management plans in industrial facilities across the globe despite minimal pushback.

. From Drain to Drink - water reuse for potable water applications Reclaimed water has proven to be more sustainable and cost-effective than developing other alternative supplies:

Reused water is environmentally sound as it alleviates pressure on freshwater sources and natural systems

It's safe - water is purified to meet the strictest water quality standards

It's sustainable - wastewater is a constantly renewable source of freshwater

It’s locally controlled - communities are not obligated to drain natural water resources or rely on neighboring countries for their water supply, leading to full water independency

. Taking Conventional Water Reuse to the Next Level Standard water reuse usually includes Ultrafiltration (UF), Reverse Osmosis (RO) and Ultraviolet Advanced Oxidation Process (UV/AOP) units. Chloramine, which is typically dosed in the RO process, helps control the membranes' biofouling. However, chloramine is a precursor to the formation of disinfection byproducts such as NDMA - a dangerous organic contaminant and a suspected carcinogen.

The presence of chloramine not only increases the risk of membrane oxidation in the case of overdose, but also acts as a free-radical scavenger, is more energy-intensive and requires larger treatment systems that demand higher CAPEX and OPEX.

. Solutions such as Pulse Flow Reverse Osmosis (PFRO™) enable a completely chloramine-free water reuse process to overcome this problem. As opposed to standard RO systems that operate under continuous hydraulic and osmotic conditions, PFRO™ utilizes alternating hydraulic conditions, switching between dead-end production mode and flushing mode, during which brine is flushed out at high velocity.

The constantly changing hydraulic conditions make it very hard for microorganisms to sustain themselves, reducing the risk of biofouling and scaling. This allows the system to operate at very high flux rates (50 percent higher than usual), eliminating the risk of a rapid increase in biofouling and resulting in overall CAPEX savings of about 20 percent.

Our ground and surface water supplies are at risk of overuse worldwide, and it’s only a matter of time before demand will surpass water supplied by rain, rivers, lakes and reservoirs. Because of that, water conservation and reuse are gaining more focus as sustainable, feasible and practical methods to alleviate industrial and municipal water demand and ensure water resilience for generations to come.

Making Every Drop Count: Recycling Municipal and Industrial Wastewater for a Sustainable Future

Lior Eshed