Building India’s Wastewater Treatment Infrastructure
India’s water quality management challenges are growing with rapid growth in urban population and fast industrialization, resulting in steady increase in the volume of wastewater generated annually causing serious threat to ecosystem and public health.
Though there has been a steady expansion in the capacity of wastewater treatment plants over the past 20 years, this expansion is not keeping pace with the rapid population and economic growth. Also in some cases, the existing capacity is not fully utilized. In most cases this is due to lack of pipeline networks to bring the sewage to the treatment plants. Often, not enough money is set aside for O&M costs. Lack of adequate staff for O&M and water quality monitoring are also issues.
Upgrading of the old wastewater treatment plants is needed for better treatment of the sewage. New wastewater treatment systems need to be constructed. Often there is too little clarity on the nature and size of the benefits and who would be benefitted.
Cost Dynamics of Wastewater Treatment
Higher levels of treatment of wastewater to improve the environmental performance would increase the cost of the plant, but may not increase the value of the benefits proportionately, especially the direct economic benefits, thereby adversely affecting economic viability.
The economics of wastewater treatment is determined by the cost of the treatment system and the economic value of the treated water. For most land-based WWT systems, the cost is a function of the land area required for treatment. In many of India’s cities, land prices are rising to astronomical levels. Here the system will be economically viable only if the amount of land required for treatment is low. But the land area required for treatment and therefore the cost is dependent on: the technology used for treatment, which is decided by factors such as temperature, altitude, soils and geo-hydrology. The land area required, and therefore the cost of removal per unit weight of pollutant, also depends on the degree of treatment required, a function of the pollutant concentration.
Economic Viability of Wastewater Treatment
The economic value of the treated water depends on the kinds of opportunities that exist for reuse of wastewater. Four scenarios can be observed in India: (1) very high demand for the wastewater for irrigation, where currently untreated wastewater is used; (2) no demand for wastewater for irrigation or fisheries, so it has to be disposed into streams; (3) no demand for wastewater in irrigation, but some water demand for growing fish; and, (4) untreated wastewater is not used for irrigation or fisheries, due to high toxicity.
The first situation is most common in arid and semi-arid areas, with considerable use of wastewater in the peri-urban areas of Delhi, Hyderabad, Ahmedabad, Bangalore, Vadodara and Jaipur for agricultural production. The second situation is possible in humid, high-rainfall regions like Kerala and Assam, where plenty of water is available for irrigation and fisheries. The third situation is common in sub-humid areas like Kolkata and Bhubaneswar, in eastern India. Here, communities use wastewater because it contains nutrients from food waste. The fourth situation is encountered in industrial areas, where the trade effluent has toxicity high enough to cause soil degradation, and where farmers have alternative sources of irrigation water.
In the first case, the cost of treating the wastewater should be less than the incremental benefits of reducing health risks to the irrigators, reducing soil degradation, and reducing groundwater pollution. In the second and third case, the cost of the treatment system should be less than the benefits of improving the general environmental quality of the river and aquatic life. In the fourth case, the cost of the treatment system should be less than the marginal economic outputs from crops irrigated with wastewater and the reduction in public health costs associated with disposal of effluents into streams.
Complex Considerations
There are complex considerations involved in the economic evaluation of WWT systems, that is, in determining both the cost of the systems and the economic value of the benefits from the use of treated wastewater. The benefits are of three types. First is the direct benefit. It depends on the incremental value of the outputs generated from the use of the treated water in agriculture, fisheries, and so on.
The second type of benefit is the ecological benefit. In areas where the untreated wastewater is used for irrigation, the improvement in the quality of cultivated soils owing to the use of treated wastewater becomes the ecological benefit. The investment required to reclaim the degraded soils can be considered as its economic value. The improvement in the quality of water in rivers and lakes is also a quantifiable ecological benefit. The economic value of this ecological benefit depends on the overall improvement in environmental conditions and willingness to pay for healthy ecosystem.
The third type of benefit is the indirect benefit, which is resulting from the positive externalities induced by the reduction in pollution of water bodies that was earlier occurring due to the disposal of untreated effluent into the rivers.
To what extent these benefits can be realized depends very much on the local socioeconomic and ecological conditions.
In water-scarce areas, direct economic benefits are likely to be high, as the value of the incremental benefits accrued from the use of treated wastewater for crop production would be high. As regards ecological benefits, in economically prosperous localities, the willingness to pay for a given degree of improvement in ecological status of water bodies and agricultural land be generally high. Again, such willingness will be more in areas where rivers experiences environmental water stress.
As regards the indirect benefits, the local conditions would determine their size and value. In areas where the communities depend on river water or the underlying groundwater for drinking purpose after treatment, the saving in the capital and O & M cost of infrastructure required for treatment of the polluted water to prevent adverse public health outcomes becomes the indirect benefit.
Conclusions
The investment decisions for wastewater treatment systems should be based on proper quantification of costs and benefits. In this regard, assessing the ecological benefits and indirect benefits of WWT systems would require characterization of the water use and reuse systems and the socio-economic systems that depend on the water systems for social, economic, and environmental uses. India needs to build its skills in the use of scientific tools for this.
Writer: M. Dinesh Kumar, Executive Director – Institute for Resource Analysis and Policy
