precipitation of calcium carbonate in geotextile envelops of agricultural rains in laboratory conditions

abstract a previous study on agricultural drains in khuzestan province of iran has indicated that carbonate calcium is the main component of the deposited salts in drainage envelops. to investigate the process of precipitation of carbonate calcium under different conditions including chemical, bio-chemical, aerobic and an-aerobic, a through laboratory investigation on geotextile drain envelop was conducted. the results of the studies showed that activity of the micro-organisms in aerobic conditions causes an increase in the bicarbonate content and consequently, increase in the ph of the medium. any increase in ph would intensify the precipitation of carbonate calcium. the results also indicated that due to the activity of micro-organisms, more than 90% of existing calcium would be precipitated. while in a chemical environment, only 30% of existing calcium would precipitate. thus, in a biochemical environment, micro-organisms would cause more calcium to be deposited. the results also indicated that the activity of the bacteria would cause formation of bio-films which in turn would provide a more suitable environment for precipitation of salts. by intensifying deposition of salts, there is higher potential for clogging of the drainage envelops including geotextile filters.