DRYING SEDIMENTARY PRODUCTION OF SEWAGE WATER IN NATURAL CONDITIONS
Industrial sewage sludge poses a considerable threat to the environment due to the high level of humidity and due to the fact that it contains pathogenic microorganisms and heavy metals ions in quantities that considerably exceed threshold limit value. The article covers the results of a study regarding the drying of sewage sludge produced by a tannery in natural conditions indoors (controlled conditions) and outdoors, with temperatures below and above zero at different times of the year (production testing). The study discovered that humidity of sewage sludge produced by a tannery can be reduced within 2 months from 85% to 10,8% due to the drying technology in natural conditions at a temperature of 20 °С. If the drying procedure takes place in form of briquets at a temperature of 20 °С the size of the briquet would be reduced by 8,1 times, its mass - by 6 times, its linear size - by half. Sewage sludge drying conducted outdoors in winter progresses slowly and affects only the uppermost layer of 5-10 cm; in summer the drying process progresses faster and within the time frame of 20 days the humidity of the sludge is reduced from 85% to 70%. Rotation of defrostation, drainage, drying and freezing procedures is conducive to a specific, more powdery sludge than the one that is produced by using only the drying procedure with temperatures above zero. A dewatered sludge can be used to produce LECA (lightweight expanded clay aggregate). The article provides generalized statistics of study results regarding the sludge drying procedure in natural conditions in contrast to the geotube method.