Most cremation units come complete with their own air pollution devices. Some of the older crematoriums, however, need to add other devices to meet current regulations. The efficiency of a cremation unit to reduce pollutants depends largely on the design, upkeep and operation of the equipment. Due to the nature of the effluent some pollutant removal methods are better than others are. The following are methods used both in the United States and other parts of the world in crematoriums.
Methods:
Controlling:
Controlling is one of the best ways to control pollutants in a cremation process. Controlling entails measuring certain properties of the circulating air and adjusts to meet the desired operating points. Temperature, Opacity, CO and O2 are measured during the process to ensure complete combustion and meet required pollutant limits. The unit can control these properties automatically by adjusting valve positions to alter the equipment's current operating point. The newer units can display the desired operation pints as well as the current operating points. Some units can even record when changes to the system were made and what was altered to achieve the desired operating point.
A wet scrubber is an air pollution control device tat is normally added to an existing crematorium that is not meeting pollutant requirements. Gases exit the cremation unit and are blown through the wet scrubber. In the wet scrubber the air is sprayed with water to remove as much air pollutants as possible from the stream. The droplets containing the pollutants gather at the bottom of the wet scrubber and are drained out. The water stream is then taken to a holding tank where the heavy particles settle out. The water can then be reused in the wet scrubber or can be disposed of after referring to the local or state regulations. Wet scrubbers are seldom used in crematoriums because the pollutant removal benefit does not outweigh the cost of the equipment.
A bag house is an air pollution control device that is also attached to an existing crematorium. In a similar manor to a wet scrubber air is directed from the cremation unit to the bag house. The size of the filter bags fitted in the bag house depends on the pollutant concentration in the air stream as well as the airflow from the cremation unit. The bags usually have shaker arms that are used when the bags need to be cleaned. The dust is collected at the bottom of the bag house and is then disposed of. The crematoriums that have a bag house to reduce their pollution emissions need to install a cooling system to cool the air stream before it reaches the bag house. Most bag houses can not handle temperatures above 500 degrees Fahrenheit. If the air stream is not cooled it could lead to the bags catching on fire. Bag houses are not generally required but some are in place in the United States. These bag houses have proven not to be very efficient at removing pollutants from crematorium emissions.
Ambient dust collectors are air pollution devices used primarily to remove dust before the operator breathes it in. The ambient dust collector has internal filters, like bag houses, but does not function to that scale. The collector is not used during the cremation process so it is not exposed to as high a temperature as the other devices. There are currently both portable and stationary models available for purchase. This device has proven to be very efficient at protecting the operator from dust exposure.