Home » Vox Pop: Experts provide solutions for urban wastewater management

Vox Pop: Experts provide solutions for urban wastewater management

Vox Pop: Experts provide solutions for urban wastewater management

From what model of PPP will work in our urban wastewater management to how they can move from a mostly secondary treatment to tertiary and make water viable, policymakers, city administrators and wastewater practitioners offer solutions.

How can our cities have better wastewater management systems? Where specifically do they need to invest? What is the cleanest cycle that a city can employ?

Roy Chowdhury
Wastewater management has two aspects: collection and treatment. These are two aspects of management—management of wastewater collection and transport system, and the other is management of wastewater treatment system. My expertise is in the collection system.

A near-zero discharge system is almost a utopian idea. You have to have a mathematical modelling system, events have to be envisaged on real time basis, every constant in the model should help us visualise what will happen in terms of flow through the collection system, in terms of pollutant load in the collection system, etc. Constants need to be inserted in the model and the outcome should be derived by a totally mathematical modelling process so that it can be verified with the actual system that has been set up in urban complexes and other areas. After verification, should there be any discrepancies between the mathematical model and real time events (practical use), there should be an inbuilt capacity in the model, wherein the constants can be manipulated or tweaked to achieve the perfect assumption or application. In my opinion, this will be the crux of the solution.

India is in infancy in terms of water and wastewater treatment. Most of the water supplied does not meet quality and sewage treatment is in very bad shape. There is need for significant investments in the sector. As the investments are to be invested by local governments, where cash is constrained, it is necessary for national level intervention through policy and financial framework to solve the problem. I strongly feel BOT/ PPP approach through private financing would be most appropriate.

Technologically it is best to go for advanced technologies as this will solve long term problems and the best approach would be a wastewater recycling technology through the zero discharge approach.

One of the best ways for our urban centres to have better wastewater management systems is to implement decentralisation coupled with upgrading existing treatment systems. Decentralised wastewater treatment systems for all major residential colonies, offices and commercial complexes will ensure that the wastewater generated at these complexes is treated to a level that is suitable for recovery and recycle. This water can be then reused in the complexes themselves for secondary uses like gardening, vehicle washing, as well as for toilet flushing. This will ensure that the existing sewage networks are not over loaded and the intake requirements of fresh water for these communities are also greatly reduced.

The central sewage treatment units can be upgraded to meet better discharge standards including reduction of nutrients that ensure that the treated water is suitable for reuse. Prospects for reuse include industrial make up, agriculture, etc.

A combination of effective decentralised wastewater treatment units and upgrading existing sewage treatment units will ensure that the treated water is effectively reutilised thereby avoiding discharge as well as considerably reducing the intake requirements of fresh water.

First, each and every cluster of buildings should have wastewater management systems. Townships are coming up, and it should be mandatory to have the waste management and recycle system. Investment should be jointly made by societies/builders and municipal corporations. Municipal corporation’s involvement is necessary as they are the planning body for the city and they decide the common drainage systems for the city.

Water and even wastewater is a non-revenue item for most municipalities, so while our due diligence for the customers on the industrial side is quite thorough—that can be done through market rating—payment risk on industrial side is not as much of a problem as it is on the municipal side.

With most contracts, what we try to do is focus more on multi lateral, bilateral funded jobs so as to ensure timely payments which allow us to then complete the project on time as well.

Most of our cities do not have proper treatment of wastewater. What should the government do further to promote the concept, to train cities, or to ensure implementation in any other way?

Presently, most of the cities in India treat wastewater only to the secondary level of treatment, which is suitable for surface discharge. In all these places, there are a good amount of opportunities to opt for tertiary treatment, making it suitable for reuse. This serves the twin objective of getting rid of the wastewater and also minimising the raw water demand.

Till 2000, many of the cities in Karnataka other than Bangalore and parts of Mysore were not provided with a sewerage system. UGD work in many of our urban centres have now been taken up under Asian Development Bank (ADB) or World Bank (WB) aided projects. Due to groundwater pollution, soak pits or septic tanks and open flows are now discouraged. Along with the sewerage system, treatment plants will also be installed. Many of Karnataka’s ULBs have now begun recruiting environmental engineers. Consultants are also appointed for preparation of DPR and implementation of projects. Providing training facilities for operation and maintenance is also included in the Terms of Reference. Therefore capacity building for wastewater treatment has been taken up seriously.

Recycling is an almost obvious solution. For example, Bangalore has a huge problem because of the Kaveri river dispute, and it gets inadequate supply of water for drinking water purposes, while the wastewater is not getting adequately treated either. So Japan International Cooperation Agency (JICA), the bilateral funding agency, is funding a series of projects to look at wastewater treatment as well as recycling for indirect potable usage not by directly converting sewage into drinking water, but by treating the water, putting it in a reservoir, and another drinking water plant is then taking it up—it makes it a little more palatable from a human consumption perspective. This is the opposite of Singapore’s treatment plan, whereby they directly take sewage going through ultra filtration and pipe it into the drinking water system.

Planning and conceptualising of solutions is paralysed by sheer conventional thinking, which cannot see beyond large scale transportation of urban waste, and building huge STPs with their huge O&M costs. Given the track record of publicly built STPs, there is no hope for the treatment, reuse, or recycling of this wastewater. Most of the existing sewage treatment infrastructure was built in colonial times and cannot cope with today’s loads. These necessarily need a revamp and reconstruction to convey increasing waste loads, due higher density of population. Lack of urban space to build STPs in the immediate vicinities is an additional challenge. Yet there is hope, if our thinking can undergo a radical transformation.

If we can shift from our current thinking that all urban waste has to be collected in bulk and treated in bulk, to decentralised management of wastewater by treating it at source, there are easily implementable solutions. Apart from saving capital costs, they can contribute to ‘greening’ of urban habitats. Thus investments in better urban wastewater management have to cover a two pronged approach.

All ‘inner city’ sewage systems need a thorough overhauling in sewage collection and transportation. Already, big cities have taken a few measures in this direction. The authorities in Kolkata have successfully revamped the sewers, built by the British in the last century, increasing the effectiveness of sewage transportation. Mumbai has constructed pipelines that convey sewage far into the sea away from the coastline. Chennai has constructed local STPs by improving localised collection and decentralised treatment. In fact the treated water is offered for industrial use.

Currently, what are our cities mainly using treated wastewater for? What is the status of your plan to recycle wastewater for domestic (non-potable) use?

We have established four tertiary treatment plants in different parts of Bangalore to use treated wastewater for non-potable uses. Two of these plants are located in the city’s biggest lung spaces, Cubbon Park and Lalbagh; water from these units is used for horticultural purposes. No groundwater is drawn for horticulture purposes. Treated water from the other plants are used for industrial use and also non potable requirements at Bangalore International Airport and other industries. Bangalore Water Supply and Sewerage Board (BWSSB) is issuing NOCs for construction and later sanctioning water supply connections to high rise buildings only when STPs are established in their premises to treat the wastewater and use the same for flushing, gardening, etc. The same procedure is followed before approving new layout plans.

We are planning to supply treated wastewater for the domestic non-potable purposes in the upcoming new layouts. For this purpose, we have recommended that the new layouts should have a dual piping system. Once the dual piping is available, we will supply treated wastewater for domestic use. There are plans to upgrade seven secondary wastewater treatment plants to tertiary level. It may take two years to commission and supply the tertiary treated water from these plants.

Wastewater utilisation is not only for industrial users, it could be related to non-industrial, non drinking structures also. For example, at Chandigarh, we treat wastewater at the tertiary level and we use that water for irrigation of the green belt, golf courses and other areas. We have a 28 mld tertiary level treatment plant. Another plant had been commissioned and has been operational for the last four to five months. The plant is being used for the irrigation of golf courses, green areas, etc, especially in the northern sector. We have taken up another project which is a Tertiary Treated Water Project under JNNURM.

We will try to sell the raw water itself, the model will be the same and the water will be treated. I think that raw sewage can be a good source of revenue. We will be unable to meet the rigid specific requirements of a client anyway, so it is a good model. In 2011, Nagpur will generate 340 mld of wastewater. Out of that, our corporation will treat 75 mld, while 130 mld will be treated by Maharashtra Power Generation Company (MahaGenCo). For the remaining quantity, we are seeking
an alternate organisation that could need this water.

In Hyderabad, our company is dealing with two specific projects which are both for wastewater recycling, and for the purpose of cleaning up the Hussain Sagar lake. Now the ultimate objective is to actually treat the sewage to a level that it would dilute the water into the lake so over a period of time the purer water would actually end up diluting the raw sewage that is being pumped into the lake. That was the end use defined by the client.

Although our power industry is the largest industrial user of water, we find that inadequate water is available for industrial processes based on priority of allocation of water, which is first for drinking water purposes, then it’s for animals, then it’s for farming, then it’s for food based industries and then for non-food based industries. In the United States, 50 per cent of fresh water consumed is in the thermal power generation industry.

This points out to first, how inefficient India is terms of its consumption of water in irrigation; but also to where our future water demand will come from. So when we are dealing with a sector which is very low in allocation of fresh water sources, they have a problem in terms of how they will treat it.

What new technologies or processes in piping, treatment, STP, maintenance, testing and monitoring systems are available as of today?

It will not be an exaggeration to say that there is no great change in the methods to treat wastewater, over the ages. But there is a revolution in new technology in materials, processes and process treatment, chemicals, and importantly, automation and instrumentation. HDPE piping is easy to handle, corrosion free pipes are available to replace all existing metal pipes. Plastics in construction of tanks and baffles and lagoon lining have transformed the levels of efficiency and effectiveness in wastewater treatment. Pumps which have remarkably superior performance in waste water and sludge handling are available.

Awareness that modern STP plants need efficient O&M needs to be driven home. A treatment unit can have over 25,000 pieces of equipment which need regular maintenance. This entails close monitoring of intermediate processes and stringent process control to obtain the final ‘acceptable’ water quality. Contract management practices can be enforced stringently.

When there is genuine scarcity of water, membrane technology is the solution for treatment of water—since it will cost higher than that in the normal course. Transporting water is cheaper than extracting it from the sea and then treating it. But currently, industries that use recycling plants are much more cost-effective than those that purchase it.

The new technologies that are available for sewage treatment include variations of the sequential batch reactor which provides treated water of a good quality and also ensures reduction of nutrients making the water suitable for surface discharge without polluting these fresh water sources. This technology also reduces the footprint required making this ideal for most large urban communities. However, for decentralised treatment, various compact and standardised treatment packages exist including the Moving Bed Reactor (Fluidised Media Reactor) and the Membrane Bio Reactor.

The Membrane Bio Reactor especially provides superior quality of output making this suitable for reuse without any further polishing. This is suitable for larger urban centres as well, and the treated water can be an effective replacement for industrial raw water.

The most important aspect requiring improvements are in the UGD systems and the STPs. Technologically, in STPs the most appropriate solution would be to go for MBR technology with ultrafiltration and polishing systems.

The larger or more technology employed, the larger the difference between the input and output water quality, and the greater the quantum of electro mechanical equipment as a percentage of the total project cost. Indeed, that defines our competency as well, which is typically picking away from the civil oriented jobs. This difference has been growing quite rapidly with the burgeoning demand in market.

Some skepticism has arisen from the fact that new pipelines need to be laid for secondary or tertiary uses of treated wastewater. How would you address it from a feasibility and viability point of view?

Cost of providing TTP and also necessary piping is substantially high. Further, operation and maintenance cost of the infrastructure is also high. The cost will be around Rs 25-30 per kilolitre, if full cost recovery model is adopted. Even then it will be cheaper than the potable water supplied at present (Rs 60).

More than viability it is the practical difficulty of laying a fresh pipeline for carrying tertiary treated water in the old and core areas of the city. However, it is possible in new layouts being formed and BWSSB has made it is a necessary condition for approving new layouts.

Water travels with gravity, from one end of the city to another end. Now, if the water demand is on the other side of the city then, I have to pump across the treated water, entailing a huge cost of pumping and a separate Elevated Service Reservoir (ESR). ESRs need to be constructed where the demand is there. We also require the infrastructure and a large, well connected distribution system.

What are the business models for wastewater management in our cities?
Is PPP a good model?

At present, for meeting the bulk water requirements of industries, the infrastructure will be provided by the Board and tariff charged is based on the full cost recovery model.

However for meeting the household requirement, proposals are yet to be firmed up. Taking up the work through PPP is also one of the options under consideration.

Currently no MCA is available under PPP model, BOT with viability gap funding would be most appropriate, with rights to sell water.

PPP models will only work when there is demand: We need to first survey the demand and have an index mapping in this regard.

Similarly we need to prepare master plans (for a 30-40 year period ahead) for reuse of water within the city and region. Then we will understand whether the scheme is viable.

The ideal kind of model for executing such a STP project is to offer the project to the private player on a Design, Build, Finance, Operate and Transfer (DBFOT) model, under PPP. The contract should have a concession period of at least 25-30 years.

Under this model, the role of the ULB will be to facilitate the entry of the private concessionaire who will then be responsible for managing the construction of a new asset and long term operation and maintenance for the concession period which can be extended, or the facility created can be transferred to the ULB in satisfactory condition.

No such MCA exists in the segment of wastewater treatment as on date due to constraints like the type of technology used, area required to set up the facility, etc.

As in other sectors, a good PPP model would ensure:

• A significant tenure—15 years
• Transparency in tendering and bidding
• A time bound programme for award of the contract
• Financially, the government participation is not a must. It would be good for the private participant to bring in about 40-50 per cent of the project cost as equity.

Under PPP, the government’s contribution should give land free and pay 50 per cent of capital investment, while the private partner would pay the balance 50 per cent of capital investment. The private partner would build and operate at a minimal margin.

PPP has had some users, but its slowness is because of the lack of a centralised decision making authority. With localised decision making on a municipal basis, municipalities become responsible for the technical scheme by which they would be utilised, the allocation of that wastewater and lastly the funding of itself. In Maharashtra, the fact that cost of water is otherwise very expensive creates a commercial imperative to actually have it recycled especially for power plants. So where there is such an imperative, and municipalities start taking responsibility for water’s lifecycle or energy costs, viability will follow.

Do you find a problem with STP or piping quality in your city? How would you address post-treatment leaks and contamination, for example?

Most of the utilities use stoneware pipes and RCC pipes, etc, for sewerage works. But due to steep increase in population in the area, the sewers are overloaded—overflow in many manholes are seen. On a need based assessment higher dia sewers are now provided as a replacement, preventive maintenance work like desilting is also taken up periodically to avoid blockages and overflow leakages from sewers. New constructions are taken up with III party inspection for quality of materials and equipment for STP works. This ensures work of high quality with long durability. Spares required for replacement of worn out parts to minimise the breakdown are kept in stock and used as and when required.

We have the operational team with us, but sometimes we have a staff shortage, because in government departments, it takes a while to fill up the post. Depending on the availability of staff, we give out O&M contracts.

The rising mains of pumping stations are prone to leakages after some years, not immediately—10 years, because of the corrosive atmosphere. We intend to repair these by using new and upcoming rehabilitating techniques. In the next three to four years, a programme for the rehabilitation of rising mains will be carried out. The way it works is that we isolate the line and work on the inside lining which can handle the corrosive atmosphere for a longer time, provided there is enough material on that line. Sometimes the localised pitting corrosion exists at many places, in such cases we do up an internal lining, and that solves the problem. If the line is fully corroded and paper thin—a rare case as of now—then we completely replace the line.

But there is no measurement of leakage as of now. These pumping stations directly or cyclised, send the mains to the main pumping station from where it goes to the disposal point, we calculate the flows of the operation of pumps because that helps us understand their characteristics. But we don’t have any flow measuring instruments for the outlets or inlets, so that is very difficult to identify. But I would say no more than 10 per cent leakages are happening or it would’ve been apparent and visible.

What is the status of repair and replacement of old pipes with new (perhaps PVC) pipes that are supposed to be more hygienic and corrosion-free? Do you give operation and maintenance (O&M) contracts, and if so, how effective has the response been?

Since our pipeline diameters are large, we opt for the RCC pipes. All the STPs are being operated and maintained by private firms. We have not been facing any problems and our STPs are producing excellent quality of treated effluent. The purpose for which STPs are outsourced is paying dividends.

Roy Chowdhury
Presently, I am working on an alternative technology, hopefully replacement to concrete pipes. It’s a first in India, but is completely in vogue abroad—42 countries.

We are working on what is known as High Density Polyethylene Double Wall Corrugated piping system. It is extremely cost-effective. The lifespan of this pipe would typically be 100 years, in comparison to 30 years for concrete pipes. It has a smooth inner surface—because of the use of plastic polyethylene—which helps it carry 25 per cent more flow, using the same diameter of a concrete pipe. Therefore, if required the diameter can be reduced by a size when using such pipes. It is inert to all the chemicals that are brought down in the sewage system and storm drainage system.

As the chemicals do not adhere to the surface, such kind of pipes need very little maintenance in comparison to concrete pipes—almost zero maintenance. The flurry would be much lesser. The pipes can be easily washed with pumping. It is much longer—2.2 times more than concrete pipes—so fewer joints are required, indirectly reducing chances of leakage, infiltration or exploitation.

What growth opportunities do you see in urban wastewater management?

Roy Chowdhury
There are immense growth opportunities. The National Ganga River Basin Authority (NGRBA) said that every town that was taken up in the Ganga Action Plan (GAP) Phase 1, or the cities that are part of National River Conservation Directorate (the river action plans), should arrest the pollutant load going to the river and divert it by some means for treatment purposes. But inter city was not part of the plan.

The basic idea was to clean the water bodies. But now the NGRBA focuses on holistically sewerage systems for towns. From every household the generated dry weather flow has to be collected and transported to the plant for treatment. You can only imagine the kind of opportunities this would entail because there are so many towns and urban complexes, and all of them have to have a holistic sewerage system under JNNURM, as well as NGRBA. The prospects are enormous and in my opinion this is social engineering.

The opportunity for growth is very high as we are in a very nascent stage. I see growth that is very much higher than other sectors and would be in the range of 15 per cent CAGR easily, and more. The most predictable revenue stream would be to have recycled water being supplied to industries at cost as a futuristic solution.

Investment opportunities exist in the area of decentralised wastewater treatment systems, central treatment units, pumping stations and the collection and distribution networks for sewage and treated wastewater. For an urban community, the best possible stream will be from treating the wastewater to a quality that is acceptable for industrial make up. Long term purchase agreements with bulk industrial users will provide a long term sustainable revenue stream for the investor. However, a purchase agreement backed by the local government or a purchase agreement with the local water authority will provide a measure of security to the investor.

The Experts:

Anik Roy Chowdhury, Principal Consultant, Alom Poly Extrusions
CK Sandeep, Vice President, Ion Exchange (India)
Goutham Reddy, Executive Director, Ramky Group
KP Gwalani, Secretary, Indian Desalination Association
Nikihil Sawhney, Executive Director, Triveni Engineering
PB Ramamurthy, Chairman, Bangalore Water Supply and Sewerage Board (BWSSB)
Dr PK Tewari, Head, Desalination Division. Bhabha Atomic Research Centre (BARC)
Prakash Urade, Executive Engineer (Water Supply), Nagpur Municipal Corp
Rajiv D Mittal, CEO and Managing Director, VA Tech Wabag
Ramani Iyer, Vice Chairman, Forbes Marshall
Rishabh Sethi, Executive Director, SPML Infra
Dr Roshan Sunkaria, Commissioner, Chandigarh Municipal Corporation
S Ramachandran, Executive Vice President, Chemical and Water, Thermax
SM Basavaraju, Chief Engineer (CP&WWM), Bangalore Water Supply & Sewerage Board
VG Sahastrabuddhe, Chief Engineer (Sewerage Ops), Brihanmumbai Municipal Corporation (BMC)

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