Tuesday, May 6, 2008

The cost of replacing Chlorine

NOTE: This originally appeared on my MySpace.com blog on May 5, 2007 (see: "The cost of replacing Chlorine").

Recently the Government Accounting Office (GAO) publicly released a report they prepared in March, 2007 for the Senate Committee on Environment and Public Works, entitled: "GAO 07-480 Wastewater Facility Security". In this report the GAO looked at some wastewater facilities that, as a result of new EPA rules about protecting against accidental releases of Chlorine, decided to replace their Chlorination system with a less dangerous substitute to disinfect the outflow from the waste treatment facility.

While not a random sample of waste treatment facilities, the GAO did select a total of 206 facilities that were distributed across the country and included facilities of various sizes. Of these facilities 41% were still using Chlorine at the start of this study (2006) and of that number 24% were planning on converting to Sodium Hypochlorite (concentrated chlorine bleach) injection or Ultraviolet light disinfection techniques. None of the facilities contacted for the study used Ozone injection, the other major disinfection technique currently available.

The GAO looked in detail at the costs for 14 plants that had already converted and 9 plants that were planning on converting from the use of Chlorine. The study found that the actual capital costs of conversion away from Chlorination varied from almost $650,000 to almost $13,000,000. The costs for the plants that were planning on converting ranged from $2,500,000 to $13,000,000. The size of the plant was not the determining factor in the cost, rather a host of factors came into play, including: plant size, layout of the plant, availability of buildings to house the Sodium Hypochlorite storage tank, size of the Hypochlorite tank, and local construction costs.

The differences in operating costs also varied. Sodium Hypochlorite is more expensive than Chlorine and requires more weight of material for the same disinfection effect. The control systems are cheaper for the Sodium Hypochlorite and less electricity is necessary for the operation of the Sodium Hypochlorite system. Chlorine facilities require fewer deliveries and Chlorine does not decompose over time as does Sodium Hypochlorite. The regulatory burden is less for the Hypochlorite Plant as it is not a Highly Hazardous Chemical and Chlorine is. As a result, some plants had some slightly higher operating costs and some had slightly lower costs.

The one thing that is not mentioned in the GAO report is that pH controls are also necessary for the Hypochlorite plant since low pH converts the Hypochlorite to Chlorine gas. OSHA does not recognize reactive hazards in their regulatory requirements, even though the Chemical Safety Board has tried to get them to change this for a number of years. The GAO report glosses over this problem, even mentioning that Sodium Hypochlorite spills are easier to clean up since it is a liquid instead of a gas. This is true until some improperly trained responder does something to lower the pH of the solution and Chlorine gas is given off as a byproduct.

Even worse, the combination of Sodium Hypochlorite and Muriatic Acid (dilute Hydrochloric Acid) or Ammonia forms an explosive mixture that produces Chlorine gas as a byproduct; ask anyone in the pool supply or pool maintenance business. While the explosion is seldom very destructive, it is not a high explosive after all, it does tend to spray un-reacted acid or ammonia around while exposing a large number of people to Chlorine gas.

From the point of view of trying to keep Chlorine out of the hands of terrorists, however, this change from Chlorine disinfection to Sodium Hypochlorite or, even better, UV radiation, is a good thing. No one told these plants they had to change, the government just made them take a hard look at the security costs of continuing to operate with Chlorine and they decided on their own that it would be better for them to switch. This is one of the ideas behind the DHS security rules; make companies play on a level playing field as to the security costs associated with various dangerous chemicals. Then allow them to decide whether the security costs are higher or lower than the cost of switching to other inherently safer technologies. As more people switch to the newer technologies, the cost of continuing the less safe technologies will continue to rise as the prices of the newer technologies drops. This will drive even more people to switch.

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