Some of the most critical maintenance issues regarding air scrubbers and air strippers are scaling, fouling and disinfection. Scaling is the precipitation and deposition of water-insoluble salts on to column internals and plastic tower packing. Fouling is the formation of deposits other than salts and which may be due to corrosion or biological growth. Disinfection is required if the water is required to be potable or safe for human consumption. It is important that these potential issues are addressed an any maintenance program to help ensure optimal performance from your system.
Scaling can be one of the more complicated maintenance issues to deal with and requires constant attention. In order to prevent scaling the water pH must be adjusted by adding strong acids and bases to prevent salts from building up. It should be noted that the geometry or configuration of plastic random packing has little or no affect in regards to scaling. The rate of scale build-up on column internals is directly related to the water quality. Ammonia and Hydrogen Sulfide are two of the most common water contaminates which require that the water pH be adjusted so that effective air stripping and scrubbing can occur. Ammonia is a weak base while Hydrogen is a weak acid. The hardness and pH of the water must be maintained to prevent scaling problems due to water contaminates such as Ammonia and Hydrogen sulfide.
A maintenance program which includes regular evaluation of the water quality in an air stripping or scrubbing column is the best way to avoid costly shutdowns, repairs or replacements. A proper maintenance and cleaning program should be implemented, which may include acid or caustic washing of the plastic tower packing and internals. Scaling in a column can develop on plastic random packing and other internals like liquid distributors, redistributors, bed limiters or packing supports, requiring these products to be changed out for new ones. Scaling also affects the overall efficiency of a system by restricting flow and reducing liquid gas contact.
Disinfection refers to the elimination of microorganisms typically found in drinking water sources. Some of the more common microorganisms found in drinking water sources include Cryptosporidium, Giardia Lamblia and Legionella. The most common forms of disinfection include chlorination and ozonation which kill organisms by oxidation. UV or Ultraviolet disinfection, which kills organisms with ultraviolet radiation is also fairly common. Chlorination is by far the most common disinfectant in the United States of America. Ozonation is more commonly utilized in Europe.
The importance of developing a proper maintenance plan before an air stripper or scrubber goes into service can not be overstated. Protect the investment you made in your column by reducing or eliminating the affects that scaling and fouling has on plastic tower packing and internals.