Odor and taste in water are recognized as quality factors affecting the acceptability of water. In its pure form water does not produce any odor or taste. Most organic or inorganic chemicals contribute to the taste and odor of water. These chemicals originate from municipal and industrial waste discharges, from natural sources such as decomposition of vegetable matter, or from associated microbial activity, and from disinfectants or their products.

The potential for impairment of sensory quality of water has increased as a result of increased reuse of available water and expansion in the variety and quantity of waste materials. Sensory tests are useful in monitoring the sensory quality of water either for drinking purposes or processing purposes. IEH offers a range of sensory tests to maintain the quality of raw water or its effects on the finished products.

IEH has pilot plant and laboratory facilities that can be brought on-site to evaluate treatment options and develop design criteria for surface water and groundwater sources. Constituents addressed in a pilot study depend on the quality of the source water.

The regulated water quality parameters most frequently targeted in a pilot study are:

The following are examples of recent IEH pilot plant evaluations:

Developed the most effective and economical treatment strategy for addressing excess levels of manganese and arsenic in a 2,000 gpm capacity groundwater source for the City of Stanwood. Other constituents of concern were ammonia and hydrogen sulfide. Four pilot filters were operated in parallel with two different types of filter media. Of particular interest was the reduction of the level of arsenic by the two filter media with and without adding additional iron to the raw water, and breakpoint chlorination before or after filtration. The recommended treatment was iron addition with chlorine oxidation prior to greensand filtration followed by breakpoint chlorination.

A 1,000 gpm groundwater source operated by the City of Bonney Lake had slightly elevated levels of iron and manganese. Three different types of filter media and two oxidants were evaluated side by side using four pilot filters. In addition to oxidant and filter media, the effect of filtration rate on the treated water was important to minimize the foot print of the treatment plant. Pyrolucite filter media with pre- chlorination met the treatment objectives.

Iron and manganese are common constituents in many groundwater sources and need to be addressed. However, this is not always the case. At one well operated by the Northeast Sammamish Sewer & Water District, the concern was arsenic. Another groundwater source had hydrogen sulfide in addition to arsenic. The hydrogen sulfide was removed by activated carbon and both of the proprietary filtration media piloted for arsenic removal met every expectation.

Numerous studies have been published documenting the similarity of illness incidence between wastewater treatment plant employees and the general population. However, because of the nature of the raw material, the processes and the product, caution and awareness are necessary to ensure a safe workplace.

Newly emerging pathogens, re-emerging pathogens and the specter of bioterrorism-based microorganisms speak loudly for enhanced awareness in the management of risk in the treatment plant workplace. Improvements in facilities has often meant enclosing processes for odor or noise control or to enable engineering and or software control systems to work more effectively. While these improvements have not changed the treatment plant processes, they may have increased the risk of exposure to workers. Enclosed spaces for grit chambers, solids dewatering, or any other processes which generate aerosols may be enhancing the exposure to organisms previously not associated as a risk for wastewater processing, for example:

At the same time, the prevalence of certain organisms in the general community has started to rise, given the shift to a more global community. Some of these risks may not have existed due to the types of processes and studies that were performed in the '50s '60s and '70s.