Water treatment for disaster situations with particular reference to iodine as a disinfectant

2013-02-12T14:32:37Z (GMT) by Mansoor A. Khowaja
The objectives of this research were to investigate the effectiveness of iodine as a means of chemical disinfection. and storage treatment on the removal of E.coli as indicator organisms in polluted water and to investigate the application of these techniques to the provision of potable quality water in disaster situations. To demonstrate the viability. or otherwise of iodine as a means of chemical disinfection. various concentrations of iodine (0.5 to 10.0 mg/l) were employed to inactivate E.coli as an indicator organism in low quality waters prepared by adding kaolin. stream sediments. digested sludge. raw sludge and an artificial suspension of hydrazine sulphate and hexamethylenetetramine as the sources of turbidity and total organic carbon (TOe). Five turbidity and TOe ranges. three temperature levels and three pH values were also employed during the investigation of iodine disinfection. The results obtained were compared with those of an arbitrarily selected standard of 1.0 mg/l chlorine. This investigation has demonstrated that under all the conditions for which dosages of 8.0 mg/l iodine were employed. a water of virtually potable quality was obtained within a 30 minutes contact period. except those containing raw sludge of more than 7 NTU. Under none of the highest inveStigated conditions (350 C. 9.0pH and 93-100NTU) of natural water samples was a dosage of 1.0 mg/l iodine found to be an effective disinfectant. Both 1.0 mg/l chlOrine and 2.0 mg/l iodine were generally effective in the samples having lower TOe values Le. kaolin and stream sediments at all investigated turbidity. temperature and pH conditions. The above dosages were also found effective in the samples containing digested sludge at the lowest investigated ranges of turbidity. temperature and pH (5- 7NTU. 50e and 6.0pH). The diSinfecting capabilities of iodine in almost all the samples were found to decrease with an increase in turbidity. TOe. temperature and pH. An investigation was carried out to demonstrate the effectiveness of storage treatment by employing low quality water containing 5 and 100 NTU of stream sediments and raw sludge at 50. 200 and 350e and at 6. 7.5 and 9 pH revealed that the efficiency of this process v increased with the time of storage. Its effectiveness was also found to depend upon pH and temperature. Two days storage brought considerable improvement in the quality of water treated at 350C. Seven days storage inactivated more than 90% E.coli in most of the samples treated at 200 and 350C. However. for all types of water employed under all conditions of turbidity. pH and temperature. a storage of 14 days was needed to remove all E.coli. A strategy for the treatment of poor quality water in disaster situations based upon the results achieved from above investigations was prepared. An algOrithm of the decisions for urgent provision of water in disaster situations was also produced. Overall. the results obtained from these investigations indicate the potential of water treatment by storage and by using iodine as a means of chemical disinfection in disaster Situations in which only poor quality water containing a high proportion of organic matter over a range of pH and temperature values is available.