Question

4a. A water authority has decided to procure a new water treatment station by design and build. Identify and discuss the information you would advise the Client to provide for inclusion in the Contract Data

4b. What information should tenderers provide for inclusion in the Contract Data?

Answer 1

The development and implementation of water treatment technologies have been mostly driven by three primary factors: the discovery of new rarer contaminants, the promulgation of new water quality standards, and cost. For the first 75 years of this century, chemical clarification, granular media filtration, and chlorination were virtually the only treatment processes used in municipal water treatment. However, the past 20 years have seen a dramatic change in the water industry's approach to water treatment in which water utilities have started to seriously consider alternative treatment technologies to the traditional filtration/chlorination treatment approach. This paper identifies and discusses some of these "emerging" technologies.

Technology Development and Implementation Process

For a new technology to be considered it must have advantages over traditional treatment processes. These can include lower capital and operations and maintenance costs, higher efficiency, easier operation, better effluent water quality, and lower waste production. Nevertheless, for a water treatment technology to be accepted and implemented at large municipal scale, it must be demonstrated in stages. Understanding this process is necessary in order to properly plan and introduce a new technology to municipal water treatment. A typical sequence of these stages might be summarized as follows:

Stage 1: Successful demonstration in another field.

Stage 2: Testing and development at bench- and pilot-scale levels (1 to 50 gpm).

Stage 3: Verification at demonstration-scale level (>100 gpm).

Stage 4: Multiple successful installations and operations at small full-scale level (0.5 to 5 MGD).

Stage 5: Implementation at a large-scale municipal water treatment plant.

Two important milestones must be achieved in parallel with the above stages: obtaining regulatory approval and reducing costs to competitive levels. Commonly, regulatory approval is necessary by the end of the demonstration-

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Suggested Citation:"11 New and Emerging Drinking Water Treatment Technologies." National Research Council. 1999. Identifying Future Drinking Water Contaminants. Washington, DC: The National Academies Press. doi: 10.17226/9595.

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scale Verification stage (stage 3) and prior to installation at small full-scale plants (stage 4). However, for a new technology to reach full acceptance (stage 5), its cost must be competitive with that of other more conventional processes that achieve the same objective.

The time duration for each of the above stages can vary greatly depending on the technology being considered, how urgent it is to have it implemented, how long it takes for its cost to reach competitive levels, and the significance of its role in the overall water treatment train. The last factor is different from the others in that it recognizes the difference between a technology that is proposed as an alternative to filtration, for example, which is an essential component of water treatment, versus a technology that is proposed to replace a less important component such as a pump, automation, chemical feed, taste-and-odor control, or preoxidation.