Letter to the Editor
Thoughts On Achieving A New Water Treatment Paradigm
By Shlomo Sackstein
To continue on the thoughts in your July editorial (“Is a New Water Treatment Paradigm Needed”), we think that the present level of water systems needs a skilled designer and an even more proficient operator.
When a system is based on multiple chemical injections, for pH control, chlorine destruction, and possibly antiscalants– even small variations in feedwater parameters threaten to send the system out of control. When chloramine removal on a carbon bed needs close supervision and dosage of NaOH for best results, rigorous training and education is needed for the operators to allow them to be able to adapt to the dynamic changes in operation.
Since is it also common to inject chlorine to control bacteria, and this background level of oxidant also degrades softener resins, every aspect of the system can spiral out of control if the incorrect action is taken at the wrong time.
So the first need is to simplify, and make water system operation more of a science and less of an art.
The second issue is water waste and its general impact on the environment. Both softeners and carbon filters use large amounts of water for back wash, rinses, and regeneration. Depending on the specific operational parameters, about 20% of the product water is wasted in this way.
Is all this wasted water necessary?
If we add the high chloride content of the softener effluent, the environmental impact of the traditional way of treating water is very high.
A third issue is lessening manual intervention. In the modern water treatment environment, even though manpower is at a premium traditional water systems are a high drain on resources. Typical activities include the addition of salt to brine makers, make up of chemical solutions as needed, cleaning membranes, and filter replacement.
But the most time-consuming activity is the manual sanitization of pretreatment and production equipment when these have developed biofilms. These sanitization activities are either unplanned outages during the week at odd hours, or they become feverish weekend campaigns under pressure to return the system to operation for the first manufacturing shift.
Lastly, possibly the most important issue is system reliability.
Can our water systems meet all the needed criteria of microbial and chemical quality with a minimum of intervention and down time?
Presently, the answer to this depends on the skill of the designer, the knowhow of the maintenance crew, and the chance fluctuations of the feedwater quality. The quality of the equipment has an impact as well.
This needs to change. Equipment that can operate well with high fluctuation of feedwater parameters with a minimum intervention of the operators is a reasonable demand even though the present designs have remained essentially unchanged for more than two decades.
The present state of affairs is not good and operators of many modern facilities would welcome improvement in as many of these issues as possible.
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