Name of the Experiment: Bacteriological Analysis of Dugwell water

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Name of the Experiment: Bacteriological Analysis of Dugwell water Powered By Docstoc
					                       Dhaka Community Hospital
                    Two-months study of Dugwell water

                   Jabed Yousuf, Golam Mostofa, Altab Elahi,
                        Ariful Islam, Sakila Afroz Joya
                    Golam Mahiuddin, Mahmuder Rahman,
                            Quazi Quamruzzaman

    Dhaka Community Hospital, 190/1, Baro Moghbazar, Wireless Railgate,
                      Dhaka-1217, Bangladesh

Name of the Experiment: Bacteriological Analysis of Dugwell water sample (from July to August
2006)

Background:
Arsenic contamination of drinking water in Bangladesh is a major catastrophe. Therefore, Dhaka
Community Hospital (DCH) has introduced sanitary, arsenic-free dugwells in Pabna District of
Bangladesh as a safe water option. DCH encourages the use of surface water as much as possible
because continuous extraction of groundwater resulted in severe lowering of the groundwater level.
Use of dugwell is therefore, an option. The reason for selection of Pabna region was that nearly all
tubewells in several villages showed excessive levels of arsenic. In total 91.

Dugwells were installed in areas that are highly contaminated with arsenic. In 27 of the wells Water
from dugwell is pumped up to overhead tank with a capacity of 3000 L and then supplied to various
households through a plastic water-supply pipe or to some places arranged by the community for
easy collection. About 40-50 households are connected with a single main supply line.

The quality of water was maintained according to sanitary guidelines of WHO and the possible
bacteriological contamination was measured. The greatest risk to human health is from faecal
contamination of water supplies. The most important aspect of analysis is therefore to determine
whether the faecal contamination is present. Bacteriological analysis of water can confirm whether a
water supply has been faecally contaminated.

Soon after the wells were constructed, in 2001 to 2003, the water samples from all wells were
analyzed for coliform bacteria. A Delagua Kit, designed at the University of Surrey, was used to
measure the faecal coliform where membrane lauryl sulphate broth was used as a media. Faecal
Coliforms (sometimes called thermotolerant coliform organisms or E. coli) are the most appropriate
indicators of faecal pollution. Other parameters like pH, Turbidity and Electric Conductivity were
also measured. The pH can affect the efficiency of chlorine disinfections. Testing for turbidity or
cloudiness of the water can be important in determining whether a water supply is acceptable. The
samples showed uniformly low levels of coliform as reported earlier and in a peer reviewed
publication (Joya et al., 2006). In 2005 questions arose concerning the reliability of the low
measurements. Some tests were conducted in 2005 to 2006 which showed very high levels on some
tests but low on others. These results, reported in Joya et al in proof, threw doubt on the whole DCH
procedure. It seems probable that the original tests were conducted just after cleaning and sterilizing
each well with lime.
It was postulated that bacteria levels rose after cleaning to high levels. At the same time it was noted
that DCH had not used chlorine to clean the wells. Yet chlorine is an internationally accepted and
encouraged procedure. Moreover in West Bengal, Dr Meera Hira-Smith (Hira-Smith et al.2007) and
others had installed about 40 dug wells using similar procedures to those of DCH but also had added
chlorine. This stimulated us to discover whether adding ca chlorine compound would reduce the
bacteria to satisfactory levels. A much more intensive procedure was adopted of testing a sample of
20 wells every day for a month. The water samples were tested before and after adding chlotech
(Sodium hypo Chloride; NaOcl) for 2 months (July and to August 2006.).

Method of Sample Collection:
Samples were collected in plastic bottles that have been cleaned and rinsed carefully, given a final
rinse with de-ionized or distilled water and sterilized properly. Samples were collected that was
representative of the water being tested; sample ports were flushed or disinfected and aseptic
techniques were used to avoid sample contamination. Sampling bottles were kept closed until it is to
be filled. After removing stopper or cap, the containers were filled with water and the caps were
replaced immediately in order to avoid contamination as much as possible.

Chlotech Dose:
The amount of chlotech added in dugwell water was 0.2 ml/L.(millitre of Chlotech per Litre of well
water)

Results:
In the month of July (Fig 1), before adding clotech the number of Faecal coliform in all the dugwell
water samples were high according to the Probability table (by McCrady), which were extremely
high (180+) in DWP3, DWP10, DWP34. After adding chlotech, the number of Faecal coliform in the
dugwell water samples decreased to satisfactory level <10 (0-7) and the level remained low (<10) up
to 23 days in most of the dugwell water. Only the water samples of DW3 and DW7 showed higher
faecal coliform in 13 days, which were 31 and 12, respectively. However, the number was increased
to unsatisfactory level >10 after 23 days and reached from 50 to 180+ in the water samples of all
dugwells at the end of the month.

In the month of August (Fig 2), chlotech was added again in all the dugwells and before adding
chlotech the number of faecal coliform was measured which showed higher values (90 to 180+)
according to the Probability table (by McCrady) in all the water samples. The number again
decreased to <10 after adding chlotech in the water samples of all dugwells although DWP8,
DWP10, DWP29 and DWP34 still showed higher values only on the first day after chlotech addition.
The number of faecal coliform remained <10 (0 to 8) up to 22 to 23 days in most of the dugwell
water. Only the water samples of DWP2, DWP29 and DWP34 showed higher faecal coliform in 15
to 18 days, which were 25, 20 and 12, respectively. However, the number was increased to
unsatisfactory level >10 after 23 days and reached from 35 to 180+ in the water samples of all
dugwells at the end of the month.
                                 200
                                 180        Y                                200       Y
                                 160                                         180
                                                     DWP 2                   160                        DWP 3
                                 140
                                                                             140
                                 120
                                                                             120
                                 100                                         100
                                  80                                          80
                                  60                                          60
                                  40                                          40
                                  20                                          20
                                   0                                     X     0                                      X
                                       0        7   14     21       28             0           7   14     21    28
                                 200        Y                                200       Y
                                 180                                         180
                                 160                                         160
                                 140                                         140
                                 120                 DWP 6                   120                        DWP 7
                                 100                                         100
                                  80                                          80
                                  60                                          60
                                  40                                          40
                                  20                                          20
                                   0                                           0
  Fecal Coliform count/ 100 ml




                                                                         X                                            X
                                       0        7   14      21      28             0           7   14      21    28

                                 200       YY                                200
                                 180                                         180           Y
                                 160                                         160
                                 140                                         140
                                 120                                         120
                                 100                                         100
                                  80                                          80
                                  60                     DWP 8                60                    DWP 10
                                  40                                          40
                                  20                                          20
                                   0                                           0
                                                                         X                                            X
                                       0        7   14      21      28             0           7   14     21    28
                                 200                                         200
                                 180        Y                                180       Y
                                 160                                         160
                                 140                                         140
                                 120                                         120
                                 100                                         100
                                  80                                          80
                                  60                                          60                    DWP 29
                                  40                 DWP 21                   40
                                  20                                          20
                                   0                                           0
                                       0        7   14     21       28
                                                                         X         0           7   14      21   28
                                                                                                                          X
                                 200                                         200
                                 180            Y                            180       Y
                                 160                                         160
                                 140                       DWP 34            140
                                 120                                         120                    DWP 66
                                 100                                         100
                                  80                                          80
                                  60                                          60
                                  40                                          40
                                  20                                          20
                                   0                                     X     0                                              X
                                       0        7   14      21      28             0           7   14      21    28

                                                                         No. of days
Note: X axis Represent No of days & Y axis Represent level of coliform

Fig 1: Faecal coliforms count in water samples of 10 dugwells (DWP2, DWP3, DWP6, DWP7,
DWP8, DWP10, DWP21, DWP29, DWP34, and DWP66) of Pabna district in the month of July.
Faecal coliform was measured before and after adding chlotech.

 Faecal coliform (chlotech -), ● Faecal coliform (chlotech +)                                                                     Formatted: Bullets and Numbering
                                 200                                            200            Y
                                               Y
                                 180                                            180
                                 160
                                                               DWP 2            160
                                                                                                               DWP 3
                                 140                                            140
                                 120                                            120
                                 100                                            100
                                 ..




                                  80                                             80
                                  60                                             60
                                  40                                             40
                                  20                                             20
                                   0                                        X     0                                          X
                                       0           7     14      21    28              0           7     14      21    28
                                 200       Y                                    200
                                 180                                            180        Y
                                 160                                            160                            DWP 7
                                 140                                            140
                                 120                           DWP 6            120
                                 100                                            100
                                  80                                             80
                                  60                                             60
                                  40                                             40
                                  20                                             20
                                   0                                        X     0                                          X
                                       0           7     14      21    28              0           7     14      21    28
Faecal coliform count / 100 ml




                                 200       Y                                    200            Y
                                 180                                            180
                                 160                                            160
                                 140                                            140
                                 120                                            120
                                 100                   DWP 8                    100
                                  80                                             80                       DWP 10
                                  60                                             60
                                  40                                             40
                                  20                                             20
                                   0                                        X     0                                          X
                                       0           7      14      21   28              0           7      14      21   28
                                 200                                            200        Y
                                 180       Y                                    180
                                 160                                            160
                                 140                                            140
                                 120                                            120
                                 100                                            100
                                  80                                             80                      DWP 29
                                  60                     DWP 21                  60
                                  40                                             40
                                  20                                        X    20                                          X
                                   0                                              0
                                       0           7      14      21   28              0           7      14      21    28
                                 200                                             200
                                 180           Y                                 180       Y
                                 160                                             160
                                 140                                             140
                                 120                                             120
                                 100                    DWP 34                   100                   DWP 66
                                  80                                              80
                                  60                                              60
                                  40                                              40
                                  20                                              20
                                   0                                        X      0
                                                                                                                             X
                                       0           7     14      21    28              0           7      14      21    28
                                                                            No. of days

Note: X axis Represent No of days & Y axis Represent level of coliform
Fig 2: Faecal coliforms count in water samples of 10 dugwells (DWP2, DWP3, DWP6, DWP7,
DWP8, DWP10, DWP21, DWP29, DWP34, and DWP66) of Pabna district in the month of August.
Faecal coliform was measured before and after adding chlotech.

          Faecal coliform (chlotech -), ● Faecal coliform (chlotech +).                                                          Formatted: Bullets and Numbering
Table 1a: Measurement of pH and EC in water samples of 10 dugwells of Pabna District before and after adding chlotech in the month
of July, 2006. According to WHO Guideline the satisfactory level for pH is 6.50-8.50 and EC is 0-850 s.
  No. of    Dugwell 2                Dugwell 3                  Dugwell 6                 Dugwell 7               Dugwell 8
  days      pH            EC         pH           EC            pH             EC         pH           EC         pH          EC
  1.        7.03          745        8.35         320           6.81           837        7.21         853        6.84        447    Formatted: Bullets and Numbering
  2.        9.73          968        8.35         798           6.81           863        7.21         1003       6.53        892    Formatted: Bullets and Numbering
  3.        7.78          713        6.98         856           6.65           765        6.74         531        6.67        801    Formatted: Bullets and Numbering
  4.        7.21          720        6.83         386           6.59           498        6.81         478        6.84        811    Formatted: Bullets and Numbering
  5.        7.05          632        6.71         802           6.59           412        6.74         632        7.01        403    Formatted: Bullets and Numbering
  6.        6.86          682        6.67         472           6.82           462        6.68         623        6.98        829    Formatted: Bullets and Numbering
  7.        7.25          452        6.74         682           6.61           421        6.8          321        7.06        718    Formatted: Bullets and Numbering
  8.        7.08          521        7.41         422           6.54           501        6.73         442        6.93        356    Formatted: Bullets and Numbering
  9.        6.73          469        7.22         618           6.59           510        6.63         452        6.74        712
                                                                                                                                     Formatted: Bullets and Numbering
  10.       6.81          532        6.94         472           6.62           326        6.72         340        6.68        352
                                                                                                                                     Formatted: Bullets and Numbering
  11.       6.63          363        6.73         358           6.59           491        6.61         320        6.53        365
                                                                                                                                     Formatted: Bullets and Numbering
  12.       6.58          424        6.69         432           6.71           622        6.59         462        6.74        396
                                                                                                                                     Formatted: Bullets and Numbering
  13.       7.05          602        6.73         523           7.14           303        6.64         378        6.68        316
  14.       6.53          425        6.82         398           6.92           324        6.67         325        6.43        412    Formatted: Bullets and Numbering

  15.       6.32          378        6.65         362           6.59           412        6.87         612        6.55        402    Formatted: Bullets and Numbering

  16.       6.51          399        6.59         430           6.64           322        7.42         456        6.82        385    Formatted: Bullets and Numbering
  17.       6.66          303        6.75         425           6.84           301        7.2          255        7.31        246    Formatted: Bullets and Numbering
  18.       6.53          388        6.61         362           6.6            280        6.87         274        6.92        419    Formatted: Bullets and Numbering
  19.       7.11          302        6.52         290           7.24           264        6.81         402        6.73        512    Formatted: Bullets and Numbering
  20.       6.61          381        6.65         502           6.94           342        6.56         618        6.84        526    Formatted: Bullets and Numbering
  21.       6.58          358        6.9          290           6.71           402        6.82         417        6.66        368    Formatted: Bullets and Numbering
  22.       6.89          412        6.63         325           6.58           271        6.74         254        7.28        310    Formatted: Bullets and Numbering
  23.       6.67          365        6.58         301           6.69           402        6.71         325        6.89        268    Formatted: Bullets and Numbering
  24.       6.5           364        6.63         518           6.72           364        6.64         398        7.02        425    Formatted: Bullets and Numbering
  25.       7.21          345        7.32         258           7.25           357        6.98         463        6.58        359
                                                                                                                                     Formatted: Bullets and Numbering
  26.       6.56          519        6.84         361           6.91           425        6.57         528        6.64        426
                                                                                                                                     Formatted: Bullets and Numbering
  27.       6.64          356        6.58         268           6.52           301        6.68         329        6.74        245
                                                                                                                                     Formatted: Bullets and Numbering
  28.       6.54          235        6.41         422           6.38           331        6.67         256        6.84        325
                                                                                                                                     Formatted: Bullets and Numbering
  29.       6.67          425        6.65         617           6.45           269        6.59         263        6.82        420
                                                                                                                                     Formatted: Bullets and Numbering
  30.       6.78          321        6.8          422           6.59           259        6.61         243        6.31        351
                                                                                                                                     Formatted: Bullets and Numbering
                                                                                                                                     Formatted: Bullets and Numbering
Table 1b: Measurement of pH and EC in water samples of 10 dugwells of Pabna District before and after adding chlotech in the month
of July, 2006. According to WHO Guideline the satisfactory level for pH is 6.50-8.50 and EC is 0-850 s.
  No. of    Dugwell 10               Dugwell 21                 Dugwell 29                Dugwell 34             Dugwell 66
  days      pH            EC         pH           EC            pH             EC         pH           EC        pH           EC
  1.        6.76          847        8.01         596           7.03           340        6.58         894       6.45         847    Formatted: Bullets and Numbering
  2.        6.67          749        8.21         698           7.09           896        6.24         926       6.21         911    Formatted: Bullets and Numbering
  3.        7.02          789        7.21         632           6.57           523        6.84         498       6.61         619    Formatted: Bullets and Numbering
  4.        6.78          702        7.12         625           6.61           469        6.94         581       6.66         642    Formatted: Bullets and Numbering
  5.        6.8           512        7.07         781           6.65           422        6.72         571       6.57         413    Formatted: Bullets and Numbering
  6.        7.02          542        6.74         702           6.71           703        6.66         692       6.73         642    Formatted: Bullets and Numbering
  7.        7.18          412        7.32         681           6.84           802        6.54         320       6.61         713    Formatted: Bullets and Numbering
  8.        6.86          581        7.24         603           6.77           402        6.71         381       6.52         336    Formatted: Bullets and Numbering
  9.        7.21          702        7.01         463           7.11           312        6.85         427       6.64         602
                                                                                                                                     Formatted: Bullets and Numbering
  10.       6.85          426        6.76         492           6.73           462        6.71         525       6.68         381
                                                                                                                                     Formatted: Bullets and Numbering
  11.       6.5           427        6.64         727           6.83           302        6.74         301       6.91         601
                                                                                                                                     Formatted: Bullets and Numbering
  12.       6.83          482        6.69         391           6.73           601        6.64         423       6.93         416
                                                                                                                                     Formatted: Bullets and Numbering
  13.       6.73          412        7.01         326           6.83           525        6.72         312       6.61         370
  14.       6.62          339        6.95         399           6.74           364        6.38         325       6.57         421    Formatted: Bullets and Numbering

  15.       6.81          382        7.05         523           7.11           326        6.64         427       6.72         611    Formatted: Bullets and Numbering

  16.       6.55          266        6.92         371           6.91           453        6.53         617       6.57         354    Formatted: Bullets and Numbering
  17.       6.82          401        6.74         370           6.62           398        6.63         486       6.82         431    Formatted: Bullets and Numbering
  18.       7.22          369        7.36         608           7.01           410        6.94         255       6.62         303    Formatted: Bullets and Numbering
  19.       6.61          361        6.67         317           6.91           315        6.68         294       6.9          299    Formatted: Bullets and Numbering
  20.       6.58          324        6.59         256           6.71           301        7.35         356       7.05         384    Formatted: Bullets and Numbering
  21.       6.9           348        6.84         333           7.25           298        6.99         301       6.57         472    Formatted: Bullets and Numbering
  22.       7.21          482        6.91         360           7.25           380        7.01         247       6.54         360    Formatted: Bullets and Numbering
  23.       6.81          472        6.78         293           6.63           286        6.51         325       6.61         296    Formatted: Bullets and Numbering
  24.       6.68          369        6.62         410           6.97           456        6.7          376       6.83         503    Formatted: Bullets and Numbering
  25.       6.5           348        6.57         415           6.71           365        7.01         419       6.69         315
                                                                                                                                     Formatted: Bullets and Numbering
  26.       6.66          321        6.71         256           7.21           412        6.99         429       6.54         601
                                                                                                                                     Formatted: Bullets and Numbering
  27.       6.69          499        7.2          362           6.94           351        6.56         405       6.57         589
                                                                                                                                     Formatted: Bullets and Numbering
  28.       6.47          342        6.95         315           6.61           321        6.62         298       6.68         254
                                                                                                                                     Formatted: Bullets and Numbering
  29.       6.59          325        6.61         441           6.63           320        6.74         521       6.52         258
                                                                                                                                     Formatted: Bullets and Numbering
  30.       6.68          512        7.21         312           7.2            250        6.8          325       6.71         350
                                                                                                                                     Formatted: Bullets and Numbering
                                                                                                                                     Formatted: Bullets and Numbering
Table 2a: Measurement of pH and EC in water samples of 10 dugwells of Pabna District before and after adding chlotech in the month
of August, 2006. According to WHO Guideline the satisfactory level for pH is 6.50-8.50 and EC is 0-850 s.
  No. of    Dugwell 2               Dugwell 3                  Dugwell 6                 Dugwell 7                Dugwell 8
  days      pH           EC         pH           EC            pH             EC         pH           EC          pH          EC     Formatted: Bullets and Numbering
  1.        7.03         745        8.35         320           6.81           837        7.21         853         6.84        447
                                                                                                                                     Formatted: Bullets and Numbering
  2.        7.89         975        8.23         892           6.97           863        7.12         1003        7.01        892
                                                                                                                                     Formatted: Bullets and Numbering
  3.        7.78         713        6.98         856           6.65           765        6.74         531         6.67        801
                                                                                                                                     Formatted: Bullets and Numbering
  4.        7.21         720        6.83         386           6.59           498        6.81         478         6.84        811
                                                                                                                                     Formatted: Bullets and Numbering
  5.        6.98         635        7.82         721           7.13           350        6.54         482         6.82        746
  6.        7.25         694        7.53         677           6.95           490        6.81         522         7.02        647    Formatted: Bullets and Numbering

  7.        7.11         820        6.82         702           6.56           577        7.22         390         6.8         641    Formatted: Bullets and Numbering

  8.        6.45         645        6.9          753           7.12           851        7.2          456         6.84        485    Formatted: Bullets and Numbering
  9.        6.54         547        7.14         631           6.84           741        7.01         654         6.71        358    Formatted: Bullets and Numbering
  10.       7.64         822        8.01         456           7.41           358        6.85         465         7.4         846    Formatted: Bullets and Numbering
  11.       6.74         524        6.71         546           7.12           834        6.58         581         6.91        743    Formatted: Bullets and Numbering
  12.       6.63         802        6.57         475           6.94           723        6.34         654         7.43        630    Formatted: Bullets and Numbering
  13.       6.71         586        6.83         654           6.71           753        7.11         564         6.82        820    Formatted: Bullets and Numbering
  14.       6.57         624        6.53         358           7.41           425        6.61         458         7.01        562    Formatted: Bullets and Numbering
  15.       6.73         701        6.54         452           6.88           368        7.41         753         6.91        423    Formatted: Bullets and Numbering
  16.       7.05         528        6.61         604           6.47           423        6.91         630         6.31        458    Formatted: Bullets and Numbering
  17.       6.53         680        6.45         582           6.68           459        6.73         630         7.02        258
                                                                                                                                     Formatted: Bullets and Numbering
  18.       7.04         358        6.64         452           7.11           652        6.35         359         6.61        478
                                                                                                                                     Formatted: Bullets and Numbering
  19.       6.71         444        6.83         580           6.92           582        6.87         490         7.23        632
                                                                                                                                     Formatted: Bullets and Numbering
  20.       6.68         654        6.71         750           7.15           652        7.31         453         6.93        581
                                                                                                                                     Formatted: Bullets and Numbering
  21.       7.36         528        7.14         398           6.83           458        6.48         571         6.67        635
                                                                                                                                     Formatted: Bullets and Numbering
  22.       7.13         684        6.81         458           6.73           842        6.58         682         7.25        458
  23.       6.49         582        6.71         470           6.48           652        6.98         478         6.81        523    Formatted: Bullets and Numbering

  24.       6.69         824        6.48         475           7.26           589        7.41         642         6.91        625    Formatted: Bullets and Numbering

  25.       7.12         586        6.68         785           6.78           653        6.69         458         7.25        369    Formatted: Bullets and Numbering
  26.       7.12         805        6.68         706           6.78           620        6.69         580         7.25        609    Formatted: Bullets and Numbering
  27.       6.65         725        6048         654           7.25           365        7.36         459         6.94        587    Formatted: Bullets and Numbering
  28.       6.58         589        7.31         654           6.59           458        6.78         694         6.64        504    Formatted: Bullets and Numbering
  29.       6.58         698        7.31         589           6.59           587        6.78         560         6.64        682    Formatted: Bullets and Numbering
  30.       6.94         458        6.48         369           6.73           456        7.26         357         7.51        452    Formatted: Bullets and Numbering
  31.       7.01         357        6.69         639           6.89           546        6.84         573         6.74        541    Formatted: Bullets and Numbering
                                                                                                                                     Formatted: Bullets and Numbering
Table 2b: Measurement of pH and EC in water samples of 10 dugwells of Pabna District before and after adding chlotech in the month
of August, 2006. According to WHO Guideline the satisfactory level for pH is 6.50-8.50 and EC is 0-850 s.
  No. of    Dugwell 10              Dugwell 21                 Dugwell 29                Dugwell 34              Dugwell 66
  Days      pH           EC         pH           EC            pH             EC         pH           EC         pH           EC     Formatted: Bullets and Numbering
  1.        6.76         847        8.01         596           7.03           340        6.58         894        6.45         847
                                                                                                                                     Formatted: Bullets and Numbering
  2.        7.02         719        7.59         698           7.45           896        6.35         926        6.54         911
                                                                                                                                     Formatted: Bullets and Numbering
  3.        7.02         789        7.21         632           6.57           523        6.84         498        6.61         619
                                                                                                                                     Formatted: Bullets and Numbering
  4.        6.78         702        7.12         625           6.61           469        6.94         581        6.66         642
                                                                                                                                     Formatted: Bullets and Numbering
  5.        6.73         850        8.02         743           7.05           654        6.45         391        6.31         478
  6.        6.71         789        8.26         805           7.12           712        6.7          456        6.99         358    Formatted: Bullets and Numbering

  7.        6.66         589        7.43         710           7.01           699        7.14         741        6.58         654    Formatted: Bullets and Numbering

  8.        6.35         654        6.45         841           6.81           702        7.23         634        7.2          741    Formatted: Bullets and Numbering
  9.        6.83         741        7.43         654           6.6            685        6.7          713        6.54         654    Formatted: Bullets and Numbering
  10.       7.31         471        6.51         465           6.31           586        6.47         357        6.85         456    Formatted: Bullets and Numbering
  11.       6.74         654        6.85         753           6.64           685        7.11         452        7.05         368    Formatted: Bullets and Numbering
  12.       6.74         523        7.11         471           7.23           560        7.01         434        6.75         568    Formatted: Bullets and Numbering
  13.       6.91         756        6.62         562           7.13           452        6.91         380        6.45         472    Formatted: Bullets and Numbering
  14.       7.32         701        6.92         621           6.85           534        6.54         480        6.58         631    Formatted: Bullets and Numbering
  15.       6.45         358        6.58         520           6.61           735        7.52         645        7.22         502    Formatted: Bullets and Numbering
  16.       6.38         380        7.23         475           7.41           289        6.74         354        6.93         425    Formatted: Bullets and Numbering
  17.       6.58         478        6.47         569           6.81           325        7.12         452        6.58         365
                                                                                                                                     Formatted: Bullets and Numbering
  18.       6.48         563        6.91         632           7.25           486        7.06         534        6.68         478
                                                                                                                                     Formatted: Bullets and Numbering
  19.       7.51         701        6.58         369           6.75           581        6.38         654        6.64         390
                                                                                                                                     Formatted: Bullets and Numbering
  20.       6.88         325        6.73         648           7.25           521        6.65         456        7.15         412
                                                                                                                                     Formatted: Bullets and Numbering
  21.       6.71         486        7.31         524           7.12           639        6.59         842        6.61         589
                                                                                                                                     Formatted: Bullets and Numbering
  22.       7.32         654        6.98         658           6.84           470        6.67         452        6.98         369
  23.       6.71         398        7.25         571           6.7            589        7.34         680        6.98         369    Formatted: Bullets and Numbering

  24.       6.58         478        7.11         523           6.51           698        6.72         741        6.68         684    Formatted: Bullets and Numbering

  25.       6.98         658        6.75         589           6.697          574        6.81         631        6.85         298    Formatted: Bullets and Numbering
  26.       6.98         521        6.75         630           6.697          456        6.81         589        6.85         658    Formatted: Bullets and Numbering
  27.       6.58         690        6.89         740           7.34           458        7.45         490        6.61         598    Formatted: Bullets and Numbering
  28.       6.82         780        7.02         630           7.01           598        6.93         630        6.78         459    Formatted: Bullets and Numbering
  29.       6.82         690        7.02         458           7.01           369        6.93         450        6.78         459    Formatted: Bullets and Numbering
  30.       6.82         365        6.71         652           6.83           452        6.57         357        6.81         459    Formatted: Bullets and Numbering
  31.       6.54         635        7.12         521           7.25           563        6.68         587        6.81         459    Formatted: Bullets and Numbering
                                                                                                                                     Formatted: Bullets and Numbering
In the month of July (Table 1a and 1b), the pH and EC values of the water samples of 10 dugwells
were in the range of WHO guideline before and after adding chlotech up to 30 days. However, on the
first day after adding chlotech DWP2 showed higher pH values (9.73) and DWP2, DWP7, DWP34 and
DWP66 showed higher EC values (968, 1003, 926 and 911, respectively). Turbidity values of the
water samples of 10 dugwells were <5 up to 30 days.

In the month of August (Table 2a and 2b), the pH and EC values of the water samples of 10 dugwells
were in the range of WHO guideline before and after adding chlotech up to 30 days. However, on the
first day after adding chlotech DWP2, DWP3, DWP7, DWP8, DWP29, DWP34 and DWP66 showed
higher EC values (975, 892, 1003, 892, 896, 926 and 911, respectively). Turbidity values of the water
samples of 10 dugwells were <5 up to 30 days.

Discussion:
The results showed that the chlorination recede the initial level of fecal coliform to satisfactory levels
according to WHO Guidelines. Then the levels stayed low in the water samples of 10 dugwells up to
23 days after adding chlotech in the month of July which was safe for drinking. After 23 days there
were some bacterial growth, which increased the number to an unsatisfactory level according to the
WHO guideline. The satisfactory level of fecal coliform was found again after addition of chlotech in
the next month, which also remained safe up to 23 days. Therefore, it was observed from the result of
10 dugwells that the water remained safe for drinking up to 23 days. The water samples were tested
before and after adding chlotech. Considerable amounts of coliform bacteria were found in dugwells
before adding chlotech.

Although this was a limited sample, in a limited time period (monsoon) in a specific area (Pabna
region) the consistency of the results in these wells suggests very strongly that regular chlorination at
least every 3 weeks can successfully keep the bacteria level low. The risk will be at the lower limit of
the rilsk estimated for a sample of dugwells of all types published in their figure 2, by Howard et al.
(2006). We are making such recommendations to the custodians of every well with which DCH has
been concerned.

Acknowledgement

We tahnk Professor Richard Wilson, Department of Physics, Harvard University, USA, and President
of the Arsenic Foundation Inc.for his encoragement and partial financial backing.

References


MM Hira-Smith, Y Yuan, X Savarimuthu, J Liaw, A Hira, C Green, T Hore, P Chakraborty, OS von
Ehrenstein, and AH Smith
Arsenic concentrations and bacterial contamination in a pilot shallow dugwell program in West
Bengal, India.
J Environ Sci Health (A) Tox Hazard Subst Environ Eng, January 1, 2007; 42(1):89-95.
Guy Howard, M. Feroze Ahmed, Abu Jafar Shamsuddin, Shamsul Gafur Mahmud, and Daniel Deere
Risk Assessment of Arsenic Mitigation Options in Bangladesh
Journal of Health Population and Nutrition Sep;24(3):346-355

Sakila Afroz Joya, Golam Mostofa, Jabed Yousuf, Ariful Islam, Altab Elahi, Golam Mahiuddin,
Mahmuder Rahman, Quazi Quamruzzaman, and Richard Wilson
One Solution to the Arsenic Problem: A Return to Surface (Improved Dug) Wells
Journal of Health Population and Nutrition 24(3):363-373 September 2006

				
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