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By Suhas Ruikar

The recycling and reuse of wastewater have gained a lot of momentum in the recent past, mainly due to the following:

  • Ever-increasing water demand.
  • Limited natural resources and erratic monsoon rainfall.
  • Cost-effective way to get water for some applications as mentioned above.
  • Restrictions of wastewater disposal and costs involved.
  • Pollution control norms and awareness of pollution control in general.
  • Confidence gained from recent successful projects of getting a better quality of treated water from sewage treatment plants.

Two main categories of wastewater treatment are: Industrial Wastewater Treatment, and Sewage Treatment. Let’s look at the sewage treatment in this article.

Growing population and urbanization has called for the need for an effective sewage treatment. The rate of implementation of such systems, at present, is very low. Only some bigger cities or towns have facilities for treating sewage effectively. These are not adequate for the size of the cities or the population. As per a study, roughly about 30 to 40% of city sewage is treated. On the all India basis, a very small percentage of sewage is actually treated. In many parts of the country, the untreated sewage is connected to rivers, polluting them, and disturbing the ecological balance.

The scope of a typical sewage treatment plant for a city covers the collection of sewage in a well, followed by primary and secondary treatment, and finally releasing the treated water to rivers/ponds. The Sewage Treatment Plants (STPs) which were/are being installed (including the ongoing projects) are capital-intense and in addition to the initial capital costs, there are other costs like operating or running costs and the costs involved in maintaining these plants.

Furthermore, the desired results are not achieved in many cases, as the outgoing treated water is not being used effectively for any application, hence the control over the outgoing treated water is almost non-existent. Projects are currently being funded through various Central Government and State Government schemes, while some projects are supported by foreign banks or by foreign funding agencies on soft loans funding basis.

The good news is that this trend (of installing sewage treatment plants) is changing slowly and a few projects can be seen having a new way of working. This is likely to continue and expected to go on a bigger scale in the near future. The STPs are expected to generate revenues to take care of initial costs and operational/ maintenance costs. There are various other benefits associated with the changing structure. Some of the broad points are discussed below.

Conventional STPs
The basic thinking behind putting up a new STP was to control pollution (damage to the river’s ecology). These schemes normally cover the collection and transportation of sewage and treatment to remove solid particles, and impurities. This treated water is then being released to the rivers or ponds or Nallas, etc. The incoming sewage has been considered a liability, as a lot of money is required to treat it.

To avoid direct disposing of sewage/ wastewater to rivers or ponds has been the basic purpose of installing STPs. The possible commercial gains coming out of the whole process were given low or no weightage. It was considered a secondary objective.

Generally, the cost structure in case of such projects has been:

  • Initially, projects cost depending on MLD sewage to be treated (capital cost).
  • Daily running cost (operational cost).
  • Maintenance cost.

Since the treated water is mostly being left to the existing rivers, ponds, etc., quality of this water was/is not prime focus area and in many cases, there was/is no strict quality control over the released water. Hence, in spite of investing higher capital costs, the desired results to the extent required are not been achieved in many cases.

Changing Scenario
In a few recent STP projects being laid down in different parts of the country, the following important issues have been considered:

  • Treating incoming sewage as an asset/opportunity to generate revenue.
  • Making the project self-standing/ commercial viable/ as a revenue-generating unit.
  • Public-Private Participation in the project to the extent possible.
  • Integration of secondary and tertiary treatment plants with RO plants in STPs.

There are various modules for investment/ funding the projects in this structure. It is a vast subject and depending on the suitability and by considering various other aspects/ parameters, a correct investment model is selected for installing an STP.

Generally, the cost structure, in case of such projects, is:

  • Initially, the project cost, depending on MLD sewage to be treated (capital cost), is by the contractor fully or partly (and partly by Government or municipal bodies).
  • Daily running cost (operational cost), by the contractor running the plant (in some cases, partly by municipal bodies/ Government schemes).
  • Maintenance cost is by the contractor running the plant.

Revenue Generation/ Payback to Contractors/ Investors

  • Revenue is generated by selling the treated water for industrial purpose or for power generation.
  • Generating electricity by using the gas generated in the process and then running the plant on this generated electricity to reduce the operational costs and selling the excess electricity, if available.
  • By selling manure.

Role of the Government

  • To make the pollution control norms stringent and monitor them regularly.
  • Make PPP model to the extent possible for the new projects and convert the older projects by adding secondary/ tertiary treatment plants (depending on the requirement), to recycle the treated water and reuse the water.
  • To make suitable rules/regulations so that for certain applications only good quality treated water should be allowed to be used (like cooling water for thermal power plants/ industrial use/ flushing water for toilets/ public gardens, etc.). In fact, it is understood that there is a rule to use the treated wastewater for cooling water application for thermal power plants in case the plant is in the vicinity of 50 kms from STPs.

Benefits of Using the Above Model

  • Cost Reduction and Quality of the Plant: As the payback/repayment is by the generation of revenue, the contractor/ investor will be very careful about the initial costs and quality of the plant/ equipment used.
    Mobilizing the resources will be much faster.
  • Saving On Time Factor: Installation and commissioning of the plant will be faster, as the revenues will start only after commissioning the plant successfully.
  • Quality of the Treated Water: The outgoing water quality will be monitored almost on a daily basis by the purchaser/ user of this treated water. Hence, there will be control over the parameters set for the treated water.
  • Saving of Fresh Water: The most significant part is the savings of fresh water (in MLD – as installed plant capacity), which otherwise would be used from the existing reservoirs for these applications. Thus, the saved fresh water can be used for other important applications.

About the Author
Suhas Ruikar is working in the field of Sales & Marketing of Pumps, and Automatic Pumping Systems etc. for over 25 years, out of which he has worked at Dubai for Building & Construction segment for about 7 years. At present, he is working as Director Marketing with a reputed pump manufacturer in India.

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