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.
X X
X X
Y
X X
X X
X X
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 +)
X X
X X
X X
X X
X X
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 +).
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 ms.
No. of days / Dugwell 2 / Dugwell 3 / Dugwell 6 / Dugwell 7 / Dugwell 8pH / EC / pH / EC / pH / EC / pH / EC / pH / EC
7.03 / 745 / 8.35 / 320 / 6.81 / 837 / 7.21 / 853 / 6.84 / 447
9.73 / 968 / 8.35 / 798 / 6.81 / 863 / 7.21 / 1003 / 6.53 / 892
7.78 / 713 / 6.98 / 856 / 6.65 / 765 / 6.74 / 531 / 6.67 / 801
7.21 / 720 / 6.83 / 386 / 6.59 / 498 / 6.81 / 478 / 6.84 / 811
7.05 / 632 / 6.71 / 802 / 6.59 / 412 / 6.74 / 632 / 7.01 / 403
6.86 / 682 / 6.67 / 472 / 6.82 / 462 / 6.68 / 623 / 6.98 / 829
7.25 / 452 / 6.74 / 682 / 6.61 / 421 / 6.8 / 321 / 7.06 / 718
7.08 / 521 / 7.41 / 422 / 6.54 / 501 / 6.73 / 442 / 6.93 / 356
6.73 / 469 / 7.22 / 618 / 6.59 / 510 / 6.63 / 452 / 6.74 / 712
6.81 / 532 / 6.94 / 472 / 6.62 / 326 / 6.72 / 340 / 6.68 / 352
6.63 / 363 / 6.73 / 358 / 6.59 / 491 / 6.61 / 320 / 6.53 / 365
6.58 / 424 / 6.69 / 432 / 6.71 / 622 / 6.59 / 462 / 6.74 / 396
7.05 / 602 / 6.73 / 523 / 7.14 / 303 / 6.64 / 378 / 6.68 / 316
6.53 / 425 / 6.82 / 398 / 6.92 / 324 / 6.67 / 325 / 6.43 / 412
6.32 / 378 / 6.65 / 362 / 6.59 / 412 / 6.87 / 612 / 6.55 / 402
6.51 / 399 / 6.59 / 430 / 6.64 / 322 / 7.42 / 456 / 6.82 / 385
6.66 / 303 / 6.75 / 425 / 6.84 / 301 / 7.2 / 255 / 7.31 / 246
6.53 / 388 / 6.61 / 362 / 6.6 / 280 / 6.87 / 274 / 6.92 / 419
7.11 / 302 / 6.52 / 290 / 7.24 / 264 / 6.81 / 402 / 6.73 / 512
6.61 / 381 / 6.65 / 502 / 6.94 / 342 / 6.56 / 618 / 6.84 / 526
6.58 / 358 / 6.9 / 290 / 6.71 / 402 / 6.82 / 417 / 6.66 / 368
6.89 / 412 / 6.63 / 325 / 6.58 / 271 / 6.74 / 254 / 7.28 / 310
6.67 / 365 / 6.58 / 301 / 6.69 / 402 / 6.71 / 325 / 6.89 / 268
6.5 / 364 / 6.63 / 518 / 6.72 / 364 / 6.64 / 398 / 7.02 / 425
7.21 / 345 / 7.32 / 258 / 7.25 / 357 / 6.98 / 463 / 6.58 / 359
6.56 / 519 / 6.84 / 361 / 6.91 / 425 / 6.57 / 528 / 6.64 / 426
6.64 / 356 / 6.58 / 268 / 6.52 / 301 / 6.68 / 329 / 6.74 / 245
6.54 / 235 / 6.41 / 422 / 6.38 / 331 / 6.67 / 256 / 6.84 / 325
6.67 / 425 / 6.65 / 617 / 6.45 / 269 / 6.59 / 263 / 6.82 / 420
6.78 / 321 / 6.8 / 422 / 6.59 / 259 / 6.61 / 243 / 6.31 / 351
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 ms.
pH / EC / pH / EC / pH / EC / pH / EC / pH / EC
6.76 / 847 / 8.01 / 596 / 7.03 / 340 / 6.58 / 894 / 6.45 / 847
6.67 / 749 / 8.21 / 698 / 7.09 / 896 / 6.24 / 926 / 6.21 / 911
7.02 / 789 / 7.21 / 632 / 6.57 / 523 / 6.84 / 498 / 6.61 / 619
6.78 / 702 / 7.12 / 625 / 6.61 / 469 / 6.94 / 581 / 6.66 / 642
6.8 / 512 / 7.07 / 781 / 6.65 / 422 / 6.72 / 571 / 6.57 / 413
7.02 / 542 / 6.74 / 702 / 6.71 / 703 / 6.66 / 692 / 6.73 / 642
7.18 / 412 / 7.32 / 681 / 6.84 / 802 / 6.54 / 320 / 6.61 / 713
6.86 / 581 / 7.24 / 603 / 6.77 / 402 / 6.71 / 381 / 6.52 / 336
7.21 / 702 / 7.01 / 463 / 7.11 / 312 / 6.85 / 427 / 6.64 / 602
6.85 / 426 / 6.76 / 492 / 6.73 / 462 / 6.71 / 525 / 6.68 / 381
6.5 / 427 / 6.64 / 727 / 6.83 / 302 / 6.74 / 301 / 6.91 / 601
6.83 / 482 / 6.69 / 391 / 6.73 / 601 / 6.64 / 423 / 6.93 / 416
6.73 / 412 / 7.01 / 326 / 6.83 / 525 / 6.72 / 312 / 6.61 / 370
6.62 / 339 / 6.95 / 399 / 6.74 / 364 / 6.38 / 325 / 6.57 / 421
6.81 / 382 / 7.05 / 523 / 7.11 / 326 / 6.64 / 427 / 6.72 / 611
6.55 / 266 / 6.92 / 371 / 6.91 / 453 / 6.53 / 617 / 6.57 / 354
6.82 / 401 / 6.74 / 370 / 6.62 / 398 / 6.63 / 486 / 6.82 / 431
7.22 / 369 / 7.36 / 608 / 7.01 / 410 / 6.94 / 255 / 6.62 / 303
6.61 / 361 / 6.67 / 317 / 6.91 / 315 / 6.68 / 294 / 6.9 / 299
6.58 / 324 / 6.59 / 256 / 6.71 / 301 / 7.35 / 356 / 7.05 / 384
6.9 / 348 / 6.84 / 333 / 7.25 / 298 / 6.99 / 301 / 6.57 / 472
7.21 / 482 / 6.91 / 360 / 7.25 / 380 / 7.01 / 247 / 6.54 / 360
6.81 / 472 / 6.78 / 293 / 6.63 / 286 / 6.51 / 325 / 6.61 / 296
6.68 / 369 / 6.62 / 410 / 6.97 / 456 / 6.7 / 376 / 6.83 / 503
6.5 / 348 / 6.57 / 415 / 6.71 / 365 / 7.01 / 419 / 6.69 / 315
6.66 / 321 / 6.71 / 256 / 7.21 / 412 / 6.99 / 429 / 6.54 / 601
6.69 / 499 / 7.2 / 362 / 6.94 / 351 / 6.56 / 405 / 6.57 / 589
6.47 / 342 / 6.95 / 315 / 6.61 / 321 / 6.62 / 298 / 6.68 / 254
6.59 / 325 / 6.61 / 441 / 6.63 / 320 / 6.74 / 521 / 6.52 / 258
6.68 / 512 / 7.21 / 312 / 7.2 / 250 / 6.8 / 325 / 6.71 / 350
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 ms.
No. of days / Dugwell 2 / Dugwell 3 / Dugwell 6 / Dugwell 7 / Dugwell 8pH / EC / pH / EC / pH / EC / pH / EC / pH / EC
7.03 / 745 / 8.35 / 320 / 6.81 / 837 / 7.21 / 853 / 6.84 / 447