Examination of processes for multiple contaminant removal from groundwater

摘要

This paper has reviewed six processes for nitrate and hardness removal for the City of Seward, Nebraska. Of these processes, ion exchange nitrate removal was shown to be the least expensive process to meet water quality regulations. However, brackish water reverse osmosis, at 12% higher cost, will not only meet the regulations, but provide an overall better water quality with substantial hardness reduction as compared to the existing water supply. It is therefore an attractive alternative. The study showed that the cost of waste disposal has a dramatic affect on the overall cost of a project. In fact, waste disposal consists of more than half of the capital cost of the ion exchange processes. This is because of the need to construct double lined evaporation ponds with leak detection devices for these processes. In other locations where a more economical waste disposal alternative exists, these costs could be substantially lowered. Again, at this location it was determined that wastes produced by membrane processes could safely be sent to the existing wastewater treatment plant. This substantially reduced the cost of waste disposal for these processes, making them more attractive. In other locations where this form of disposal is not available, substantially different disposal costs might be found. It becomes obvious that selection of the appropriate treatment process for a specific location requires careful evaluation of the capabilities and costs of the processes and of their waste handling requirements.