The Need Of Efficient Operation And Maintenance

Traditionally, the waste water treatment plants have been designed as per the conservative guidelines and standards which were a result of the gradual development in the designs made before them. The methods and procedures to be applied and followed during the operation and maintenance of a treatment plant have hardly been modified with respect to the observations made on the site. These have been passed from seniors to juniors in the operation and maintenance department without taking into account new and better approaches to improvise the plant’s function and reduce the operational costs. Most of the WWTPs have been found to have a considerable margin or amount of additional capacity beyond the capacity that was given during the design. In the plants which have a higher human participation in operation and maintenance, there is always a wide scope of improvement in the operating procedures in practice, increasing the efficiency of the units installed and reducing the maintenance expenses.

In the late 80s and early 90s, the optimization and performance improvement of the WWTPs came to light for the first time. In the United States, it was first observed that there were a considerable number of sewage and effluent treatment plants erected but most of these treatment facilities were not functioning as per their efficiency measures. With the rising energy prices and the gap between energy and supply, the concepts of audits and energy conservation were introduced in the operation and maintenance of WWTPs. The first-hand experience of applying these concepts showed that the existing facilities could be used to treat larger quantities of water at same operating costs or the same quantities of water at lower operating costs. By including the goals such as improving the plant performance, reliability, flexibility and efficiency while reducing the capital and operating costs and improving the unit operating methods and practices, the WWTP optimization practices were made a part of regular exercise in the operation and maintenance of treatment plants by late 90s.

There have been several cases where the costs regarding material and energy inputs to the plants and man hours have been considerably reduced after undertaking these optimization practices. While upgrading or renovating an existing treatment facility or designing a new one, the indices related to the capital and operating costs are mostly used to evaluate the alternatives of different treatments available and operating strategies associated with the types of treatment. Even the software tools like CAPDET or STOM and the optimization tools like have the following major drawbacks:

• The indices used to evaluate the capital and operating costs do not take into account the factors such as ease of operations or sustainability in unit operation and maintenance, but only account the cost indices associated with the erection and maintenance of the treatment facility.
• These hardly account the use of the continuous monitoring systems identified by in identifying the opportunities to reduce the operating costs.
• Majority of such software or practices developed also fail in accounting the change in the characteristic of the influent wastewater with time and hence the results generated might be precise when compared to previous documented results, but would not be accurate.

Today, there is a huge demand of such practices in the Indian context. With the persistent rise in number of industries each year and the exponentially increasing residential establishments in the urban regions, the current sewage and effluent treatment facilities would soon lose their potential to cater to the treatment demands. Developing new treatment facilities would impact the public and private financial reserves which currently are not in the best of their health. Moreover, development of new treatment facilities while the existing facilities do not function to the best of their efficiencies would add to the ecological footprint of the area or city.

Thus, in order to enhance the efficiency of the treatment plants with the existing infrastructure and with its present staff, which particularly in the Indian context is less educated, there is a need of a method which helps the operation and maintenance moderators to identify the problems in the plants, to measure each attribute or variable associated with the problem separately and correlate it with other possible attributes or variables, to analyse these correlations and determine the root cause(s) of these problems, improve the present practices in order to eliminate or avoid such bottlenecks from reducing the WWTP’s efficiency and to control these improvisations made with least input of man hours. We have developed this method with reference to the Composite Correction Program implemented in the United States and the DMAIC framework used for performance optimization in the manufacturing and service industries worldwide to increase the efficiency of the treatment process by making the exercises process dependent instead of employee dependent, establishing continuous communication and documentation practices and educating the moderators about the tools with which they could continuously monitor and evaluate the performance of their treatment facilities.