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Wetland Conservation – A Climate Change Response “Low hanging fruit for achieving mitigation milestones”

The annual celebration of World Wetlands Day is a wonderful opportunity to remind ourselves of our duty to protect and preserve the dwindling wetlands in our country. It has always been a challenge to strike a balance between the environment and the development and as is known, the latter is seen to be a sure winner in the battle. Since it is at the cost of our environment, I deem it a pyrrhic victory. We always become wise after the event.

Be that as it may, wetland conservation has now become an imperative, especially in an urban environment. The significance of wetland cannot be over-emphasized, for, it is an important groundwater recharging source, particularly for a city like Chennai. Furthermore, it is a flood regulator besides being a sanctuary, if I may say so, for a variety of birds and other species.

It is not out of place to mention here that WABAG launched an integrated program for building capacities for wetland management among the various stakeholders, followed by wetland restoration of Narayanapuram Wetland in close proximity to our corporate headquarters at Chennai, Tamil Nadu. Today, with increased water holding capacity, the wetland has become an important groundwater source for the neighborhood.

It is a good augury that the Govt. of Tamil Nadu chose to set up a State Wetland Authority which goes to show the utmost importance that is being accorded to the cause of environment.

Despite the aforesaid benefits, I find there is lack of awareness on the importance of wetland conservation among the public, nay, even some of the elite sections of the society. It is therefore urgent and necessary to create an awareness in the first place in the minds of the public.

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Myths and Misconceptions about SWRO Desalination in India

Water stress in different regions of India has made people to accept Seawater Reverse Osmosis (SWRO) desalinated water as an alternate solution to alleviate drought. However, the following myths and misconceptions still exists among a few. Clarifications are provided to overcome the myths and misconceptions.

Myth 01: Desalinated water from Municipal Desalination Plants do not have enough minerals and use of desalinated water depletes minerals from the body

SWRO plant’s design is flexible with modular and multistage arrangement to produce water of any required specification. Potable water produced is of high quality, reliable and free from bacteria and virus. The potable water from SWRO plants are designed to meet ISO 10500 standard or World Health Organisation (WHO) specification or they can be design to produce high purity Process water for Industries with Total Dissolved Solids (TDS) < 10 mg/l. Typical analysis of selected potable water parameters from a desalination plant are given below:

Hence, it is not true that potable water produced by the municipal SWRO plants do not have minerals.

Myth 02: Desalination plants kill fish and other marine life in that region

In designing desalination plants, protection of marine life is given priority. The Intake is designed providing large flow area so that water enters the Intake velocity head at very low velocity so that fish, fish eggs and other marine lives are not drawn inside. Intake velocity head is located deep inside sea. Hence, protection of marine life from being drawn along with seawater is ensured. Typical Intake velocity head arrangement is illustrated in figure 1 and 2.

Figure 1 : Intake velocity head (Bar Screen Type)

Figure 2 : wedge wire type Intake screen

Desalination Plant ensures that only salt water is discharged without any impurities or chemicals. The chemical cleaning solutions are neutralized before being discharged to the sea. Many plants remove sludge from the backwash waters before it is discharged in to the sea. The outfall discharge is located away from shore deep inside sea with the multiple nozzle diffuser design to recirculate the seawater and dilute the brine salinity closer to the seawater salinity at a radius of 50 meters, so that the fish and marine lives are not affected. The environmental protection agencies monitor the seawater quality close to the outfall.

Myth 03: Desalination Plants increase salinity of well water close to the shore

The recovery (percentage of low salinity water recovered from seawater) is in the range of 40 to 45%. The salt rejected from the 45% low salinity water separated in the RO plant is returned to the sea as brine along with 55% seawater. However, the brine gets diluted in salinity and it reaches close to the seawater salinity at a radius of 50 meters from the discharge point. Hence the salinity of the seawater near shore remains unaltered.

Myth 04: Desalinated water cost is very high and not affordable

The cost of water produced by desalination has come down considerably in the last 30 years due to developments in membranes with higher productivity, innovation in energy recovery devices, economy of high capacity units, more efficient higher capacity pumps etc. The O&M cost in Nemmeli 100 MLD desalination plant owned by CMWSSB and being Operated and Maintained by VA Tech WABAG is Rs 39/m3. New desalination technologies are bound to reduce the cost of desalinated water further. Electric power cost which forms >75% of the O&M cost of a SWRO plant in India can be brought down further by using green energy, much lesser in cost compared to power from thermal power plant.

Myth 05: Desalination consumes more energy

In 1980s, SWRO consumed around 8.5 to 9 kWh/m3 of water produced. The plant recovery was in the range of 30 to 35% and the plant capacity was much less. However, today, with innovations in the energy recovery devices, RO membranes with high flux, high capacity plants with more efficient pumps, the energy consumption has come down to 3 to 3.5 kWh/m3. Research is being concentrated in development of new desalination technologies like Forward Osmosis and Membrane Distillation Process and advanced membrane technologies like Aquaporin & graphene to bring the specific power consumption further down.

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Innovative and Developmental Technologies for Desalination – Forward Osmosis

This is an osmotic process that uses a semi-permeable membrane to separate salts from water. FO uses an osmotic pressure gradient (∆п) instead of hydraulic pressure (∆P), which is used in RO, to create the driving force for water transport through the membrane. No energy is needed to drive the water flux of an FO process, as the water flux is the natural tendency of the system. FO is an innovative membrane-based technology that has the potential to reduce the costs and environmental impacts of desalination.

The concentrated solution, or draw solution, is the source of the driving force in the FO process. A selectively permeable membrane allows passage of water, but rejects solute molecules and ions. Osmotic driving forces in FO can be significantly greater than hydraulic driving forces in RO. This results in the potential for higher water flux rates and recoveries. The selection of an appropriate draw solution is the key to FO performance.

The draw solution should have a high osmotic efficiency (that is, have a high solubility in water and a low molecular weight), be non-toxic; trace amounts of chemicals in product water might be acceptable, be chemically compatible with the membranes.

Draw solutions include magnesium chloride, calcium chloride, sodium chloride, potassium chloride, ammonium carbonate and sucrose

A simplified process schematic of an FO process using ammonium carbonate as a draw solution

Potential Advantages over Established Technologies

• FO Operates around 1 atmosphere (atm), which results in much lower energy consumption compared to conventional membrane and mechanical/thermal evaporative desalination technologies • FO Membrane compaction is not typically an issue • Has less fouling propensity compared to RO

Potential Disadvantages Compared to Established Technologies

• FO is still under development. Knowledge about the following has not been established fully: treatment efficiencies of larger-scale installations, economics, and short- and long-term performance and fouling/scaling • Requires special membranes. Existing commercially available RO membranes are not suitable for FO because such membranes have a relatively low product water flux, which can be attributed to severe internal concentration polarization in the porous support and fabric layers of RO membranes • Use of ammonium carbonate as draw solution may provide desired osmotic pressure. However, diffused ammonia to the permeate stream should be removed using a low cost technology (such as waste heat to strip ammonia)

Advancements needed for consideration of this technology in full-scale applications

• Identifying effective and economical draw solutions and technologies/approaches that remove draw solutions economically (such as using waste/low-grade heat). • Developing new and additional membrane sources. Currently, a limited number of commercially available membranes are on the market using cellulose triacetate. • Addressing mass transfer limitations resulting from concentration polarization within the membrane support layer. • Developing new modules suitable for full-scale implementation. To date, most applications have used flat-sheet, plate and frame elements.

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Ocean and its Myriad Dimensions

Our Planet Earth depends on the vitality of the ocean for sustenance in myriad ways. Ocean offers innumerable benefits to the mankind in terms of saltmarshes, mangroves, ocean currents, nutrient rich upwelling and other forms of life. As is well known, it provides for an alternative source of water which is reliable, perennial and viable and we, WABAG, with advanced technologies at its command, desalinate sea water into potable water for quenching the thirst of the citizens not only in India but also across the globe. Let us now see its other dimensions:

The ocean produces over 50% of the world’s oxygen and stores 50 times more carbon dioxide than our atmosphere. The majority of oxygen production is from oceanic plankton — drifting plants, algae, and some bacteria that can photosynthesis. Ocean plays a major role in carbon cycle. 

Carbon is continually exchanged between the ocean’s surface waters and the atmosphere, or is stored for long periods of time in the ocean depths

Covering 71% of the Earth’s surface, the ocean transports heat from the equator to the poles, regulating our climate and weather patterns

76 % Percent of world’s trade involving some form of marine transportation

From fishing to boating to kayaking and whale watching, the ocean provides us with so many unique recreational activities

Many medicinal products come from the ocean, including ingredients that help fight cancer, arthritis, Alzheimer’s disease, and heart disease

Amount the U.S. ocean economy produces in goods and services is 282 Billion USD. Ocean- dependent businesses employ almost 3 million people

The ocean provides much more than just seafood. Ingredients from the sea are found in surprising foods such as peanut butter and soymilk

Seawater contains large quantities of valuable minerals, some of which are very scarce and expensive in their land-based form. However, only a few minerals, the ones in high concentrations, are currently mined from the sea. Due to recent challenges with land-based mining industries, seawater mining is becoming an attractive option. The main ions which make up 99.9% of the salts in seawater in decreasing order are: Na+ > Mg2+ > Ca2+, K+ > Sr2+ (for cations) and Cl− > SO42− > HCO3− > Br− > BO32− > F− (for anions). Currently the four most concentrated metals – Na, Mg, Ca and K – are commercially extracted in the form of Cl−, SO42−, and CO32−. Mg is also extracted as MgO.

Deep sea mining is also growing that involves the retrieval of minerals and deposits from the ocean floor found at depths of 200 meters or greater. Presently, the majority of marine mining efforts are limited to shallow coastal waters, where sand, tin and diamonds are more readily accessible.

But our ocean faces major threats such as global climate change, pollution, habitat destruction, invasive species, and a dramatic decrease in ocean fish stocks. These threats to the ocean are so extensive that more than 40 percent of the ocean has been severely affected.

Let us minimize the threats to the ocean from Mankind so that ocean continues to offer its invaluable benefits to sustain our Planet Earth.

[vatechwabag]

Groundwater, making the invisible visible

Groundwater is invisible, but its impact is visible everywhere. Out of sight, under our feet, groundwater is a hidden treasure that enriches our lives.

Almost all of the liquid freshwater in the world is groundwater. Groundwater provides almost half of all drinking water worldwide, about 40% of water for irrigated agriculture and about one third of water supply required for industry.

It sustains ecosystems, maintains the base flow of rivers and prevents land subsidence and seawater intrusion. Despite its importance, groundwater is invisible. In addition, out of sight often means out of mind.

As climate change gets worse, groundwater will become more and more critical. We need to work together to sustainably manage this precious resource. There are also some strategies to promote sustainable groundwater supply. Conjunctive use of surface water and groundwater, desalination, recycling and wastewater reuse, water harvesting, increase recharge to the groundwater system are few effective measures to promote sustainable groundwater supply.

Groundwater may be out of sight, but it must not be out of mind. The theme of groundwater should be able to shape the campaign through suggestions of activities but also get the information and the tools needed to raise awareness of groundwater in all public forums.

The theme of groundwater will contribute to a raised public, policy and scientific awareness of the opportunities and risks of addressing groundwater in the context of achieving sustainable development goals. WABAG, the world market leader in the water industry, always stands in front for giving all necessary support in achieving this goal.

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Effective recharge of aquifers, a sustainable approach towards enhance groundwater resource

An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials. There are two general types of aquifers: confined and unconfined. Confined aquifers have a layer of impenetrable rock or clay above them, while unconfined aquifers lie below a permeable layer of soil. In order to access this water, a well must be created by drilling a hole that reaches the aquifer. While wells are man made points of discharge for aquifers, they also discharge naturally at springs and in wetlands. Aquifers are natural filters that trap sediment and other particles (like bacteria) and provide natural purification of the ground water flowing through them.

Aquifer recharge (AR) and aquifer storage and recovery (ASR) are man made processes or natural processes enhanced by humans that convey water underground. The processes replenish groundwater stored in aquifers for beneficial purposes. AR is used solely to replenish water in aquifers. ASR is used to store water, which is later recovered for drinking water supplies, irrigation, industrial needs, or ecosystem restoration projects. Injecting water into AR wells can prevent saltwater intrusion into freshwater aquifers and control land subsidence.

Several methods of introducing water into an aquifer exist including surface spreading, infiltration pits & basins and injection wells. Injection wells are used for AR and ASR in areas where surface infiltration is impractical. Aquifers can be recharged from rain water, river water, recycled water, etc.

Groundwater is one of our most valuable resources. Aquifers are nature’s storage tanks provided to mankind. We see a lot of river water being discharged to sea, during every monsoon, without being used. If the rain water & river water are effectively used for recharging aquifers, the ground water availability can be enhanced and Aquifer stored water recovered can be used to alleviate the water shortage.

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Digitization in Water Industry

Finite in water resources and end users stringent deliverable creates huge pressure on this segment which necessitates water treatment industries to deliver more efficiently including safe and secure drinking water, storm water management and waste water management. Water crisis has been indicated as one of the main global risks due to the climate change. Pandemic affected the water treatment and waste water treatment segment also. Also the pandemic didn’t spare the water industry and many people in the treatment plants were affected, which led to skeletal resources operating these huge facilities. Innovative approaches like Remote Monitoring, extensive usage of smart condition monitoring devices for the rotary equipment, application of IOT and by adopting smart monitoring sensors improve service level sustainability and economic viability. Digitization in water segment also helped in sync with other utilities like power, transport and disaster management. This leads to the operational continuity in the scheme of things.

Generally, water & waste water treatment plants in municipal and Industry are operated through SCADA (Supervisory control and Data acquisition) and PLC (Programmable Logic Controller) with sufficient interlocks and with all safety features. During this global Pandemic, to mitigate the risk of the skeletal manpower at site, one of the solutions that has come handy is to monitor the plant performance at a centralized Network operations center located at a remote location. Process experts can monitor the multiple plants located at different parts of the world. In case any abnormality is observed in the plant performance from these remote locations, an alert is issued to the site team and also provides solutions to the problems. This methodology has also been used extensively in virtual commissioning of the equipment, besides the process monitoring of the plant.

IOT’s have become handy and are being extensively used in process analyzers and instruments which can provide Real time data, trends, escalation matrix and can also communicate to the centralized monitoring stations. Presently, manual log sheets are becoming obsolete and digital log sheets, which are automatically generated from system are preferred which is an authentic data. IOT supports OPEX costs like optimizing chemicals, power, utilities and reducing wastage.

The increasing complexity in various technologies necessitates a paradigm shift to the next generation and water systems beyond conventional water and sewerage water. Conditional based monitoring services can work with all the water automation products for gaining access to real time data via cloud from remedial loaded water assets as this drives the sector shift from reactive to real time monitoring. Above digital interventions definitely involve CAPEX, however OPEX will be reduced drastically for long term plant operations. On the other hand, this will improve the reliability of equipment and plants. It is imperative that awareness and familiarization of these technologies have to be focused in various forums and webinars.

Digitization & Artificial intelligence ensures Operational excellence by way of

Lesser machinery breakdown due to usage of IOTS, smart sensors and real time monitoring

Lesser energy consumption on optimum energy usage

Optimized Chemical Consumption

Reduced water losses

Reduced contamination of water bodies

Improved customer satisfaction and transparent service level agreement

Digitization solutions allows experts to analyze data collected from smart sensors and derive into corrective and confident action to extend equipment failure

Digitization can trigger the earliest possible warning

Going forward, digitization and artificial intelligence will play a critical role in the water and wastewater treatment industry as well for ensuring Operational Excellence.

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Waste to Energy – Achieving Self-sustenance in Sewage Treatment Plant

The successful operation of a Sewage Treatment Plant (STP) not only lies with achieving the desired standards but also with value additions & overall plant operation, economical as well as technical ease. There is lot of concern on the present growing dependence on Power supply in Developing countries like India. This has driven the Wastewater treatment market to look for alternative sources of energy. Bio sludge, the major waste generated in an STP is a valuable carbonaceous resource, which can be efficiently utilized for generation of energy with well-designed Sludge Treatment units employing Anaerobic digesters, Biogas harness facilities and Biogas based GenSet systems. These systems are capable of generating electricity to fulfil the self-sustenance of the Plants, from where energy is harnessed in the form of biogas. Some of these STPs are successfully operating for more than ten years for Chennai Metropolitan Water Supply and Sewerage Board with consistent and enhanced power generation from biogas in Chennai, India. The fine-tuned operations have helped in reducing energy requirement from State Electricity Grid/Diesel Generator Set (DG) and at the same time sustaining its sole purpose, sewage treatment.

The Sewage Treatment Plants at Kodungaiyur and Perungudi are two among the four sewerage treatment plants

of Chennai City executed by WABAG during 2006. Both STPs were designed based on Conventional ASP for capacities of 110 MLD and 54 MLD respectively. Other two STPs of 60 MLD at Koyambedu and 40 MLD at Nesapakkam were executed by other contractors. In all these STPs, emphasis has been laid into sludge treatment and generation of power from biogas, utilizing the same to run the whole treatment plant thereby significantly reducing the electricity import from the State Electricity Grid.

The treatment of sewage is typically done through primary treatment for removal of solids/grit etc., followed by biological treatment in conventional activated sludge system. The primary and excess biosludge produced is thickened and digested in anaerobic sludge digestion, producing methane rich biogas and well-digested biosludge suitable for disposal after dewatering in a centrifuge. The biogas produced is collected in a gas holder and used as fuel in biogas engine (1 MW capacity) after passing the same in bio-scrubber for removal of hydrogen sulfide, which is corrosive to the gas engine.

Success of plant operation and achieving even better results is possible through close monitoring and control of process. Dedicated efforts by the technical team provides the consistent successful operations of the plant for not only achieving the desired parameters but also the energy produced by non-conventional energy has helps the environment and eases the burden of the precious resource – “Electric Power”.

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Potable Reuse – The Future Of Sustainable Water Management!

Water scarcity is one of the biggest global problems that the whole world is facing and the future could be alarming if we do not take up the right measures today. The factors contributing to water stress can easily be associated with population growth and the climate change. And hence, the world in many parts is fighting for a clean and safe drinking water.

The applicable solution here could be treatable municipal water supply which could also be a drought proof source for a potable water resource and this practice has been employed from many years now. The most exemplary and prominent examples of water treatment practices could be Water Reclamation Plant at Windhoek, Namibia, built by WABAG, Singapore NEWater (Public Utility Board) and the Orange County Groundwater Replenishment System/California (Orange County Water District). With addition to these water practices, there are also other water projects which are under development and one such project is in Texas and California where recycled water is made use of by turning it into crafted beer. Also, countries like India, South Africa and Brazil are examples of considering the effective use of potable reuse.

There is also another major water issue in this regard and that is the right provision of sufficient water treatment reliability. To define it in another way, water reclamation process is directed to achieve the desired degree of water purification by measuring it in inherent robustness, redundancy and resilience.

Talking about redundancy, it can be described as the means of employment of various individual and independent barriers that is for safeguarding the public health in times of need and requirement. And robustness directly constitutes the capability of addressing a varied variety of containments while also helping in reducing the occurrence and events of catastrophic failures. Now, resilience can be represented as the ability to quickly adapt and restore the required performance that comes in the process of threats and treatment failures.

There should also be another key factor to be considered and that is the Public Acceptance, which can only be through the right adequate and comprehensive information and educational programs in this regard.

WABAG’s aim in this matter is to simply convince people that “Water should not be judged by its history but by its quality”, as said by Dr. Lucas Van Vuuren.

Finally it will be no doubt to conclude that potable water reuse strongly advocates a sustainable solution, which in the coming medium term can be effectively and widely used as a major water management treatment and solution.