This study was conducted between September and November 2008 in Can Tho City, which is located in the centre of MD. Microbiological make-up of faecal sludge (pig slurry and septage), surface water were determined. Pathogen treatment efficacy of PBDs was also taken into account. In urban area, septage samples were taken from STs in the centre of Can Tho City. Microbial quality of aquatic spinaches cultivated in fishponds and urban canals were examined. Analyses were done at the Environmental Biology and Engineering Laboratory, College of Environment and Natural Resources, Can Tho University.
2.2.1 Samples from plastic bio-digester
Samples were taken from 18 PBDs in Phong Dien District (Figure 2.4) during the morning’s routine cleaning. Influent samples were collected directly at the biogas
digester inflow. Five-hundred ml of the inflow were collected every 20 seconds and transferred into a 40-litre bucket. The material was then stirred well and one-litre sample was taken for analysis. One-litre effluent samples were collected about 5 minutes after effluence.
Figure 2.4 | Sampling areas (coloured) within the field study in Can Tho City.
Data source: Department of Agriculture and Rural Development of Can Tho City 2009.
A questionnaire survey was conducted during sampling that included the volume and age of PBDs sampled, input sources, de-sludging conditions, and discharge/use of sludge and liquid output. The overall condition of the PBDs was also recorded during sampling.
Samples were analysed for pH, dry matter (DM), somatic coliphages, male-specific bacteriophages, Escherichia coli, Salmonella spp., Enterococcus spp., and helminth ova.
2.2.2 Samples from septic tank This part of the study examine
septage in Can Tho City to give an overview of the population’s health situation and possible uses of sludge
untreated septage was also tested since it is the effluent
effluent is often discharged directly to surface water without any treatment.
Samples were taken from Rang District (Figure 2.4)
were taken from each tank: one at a depth of 10 cm (untreated septage), the other from the centre (septage sludge) when the tanker
were full at sampling. The emptying intervals ranged from 1 to 20 years.
compartments and a storage volume of 1 number of users of ST per household ranged
No readymade inspection hatches existed in the surveyed tanks. Workers had to damage house floors as the STs were located in the basements
was transported to the neig (Figure 2.6).
Figure 2.5 | Septage desludge Samples from septic tanks
examined the pathogenic content and indicator organi
to give an overview of the population’s health situation and possible uses of sludge for agriculture and aquaculture. Besides septage sludge, untreated septage was also tested since it is the effluent of full STs. This untreated effluent is often discharged directly to surface water without any treatment.
Samples were taken from STs from 20 single-family dwellings in Ninh Kieu and Cai ) as they were being emptied by a pump truck. Two samples were taken from each tank: one at a depth of 10 cm (untreated septage), the other from the centre (septage sludge) when the tanker had extracted half the contents.
were full at sampling. The emptying intervals ranged from 1 to 20 years.
compartments and a storage volume of 1 – 2 m3 predominated (16 out of 20 tanks) per household ranged from two to ten with an average of five.
No readymade inspection hatches existed in the surveyed tanks. Workers had to damage were located in the basements (Figure 2.5). Extracted septage was transported to the neighbourhood province (Hau Giang) and discharged to a dump
Septage desludge. Figure 2.6 | Septage is discharged into a dump located in Hau Giang province.
the pathogenic content and indicator organisms in to give an overview of the population’s health situation and . Besides septage sludge, . This untreated effluent is often discharged directly to surface water without any treatment.
in Ninh Kieu and Cai as they were being emptied by a pump truck. Two samples were taken from each tank: one at a depth of 10 cm (untreated septage), the other from had extracted half the contents. All STs were full at sampling. The emptying intervals ranged from 1 to 20 years. STs with two (16 out of 20 tanks). The from two to ten with an average of five.
No readymade inspection hatches existed in the surveyed tanks. Workers had to damage Extracted septage hbourhood province (Hau Giang) and discharged to a dump
o a dump
Samples arrived at the laboratory within one hour and were stored at 4o C before analysis. Samples were processed within 24 hours of sampling with the exception of helminth ova. Analyses included pH, dry matter (DM) and somatic coliphages, male-specific bacteriophages, Escherichia coli, Salmonella spp., Enterococcus spp., and helminth ova.
2.2.3 Surface water samples
Microbial characteristics of surface water were determined in small canals in both rural and in urban areas. Surface water in rural areas receives faecal matter from animals and human beings while in urban areas the main source of faecal contamination is from humans. Moreover the usage of surface water is also different in those two areas. For instance, it is used for drinking in rural but not in urban areas, where tap water exists.
Twenty samples were taken from canals in rural areas where people bath/swim and use the water for drinking and cooking (Phong Dien District, Figure 2.4). Another 15 samples were taken from small canals in a downtown area of Can Tho City (Ninh Kieu District, Figure 2.4). Tham Tuong and Cai Khe canal were excluded because of its heavy pollution (PCCTC 2003). They are not representative of urban canals in MD.
Moreover, there is almost no bathing or swimming here due to the offensive smell. As people usually use surface water at high tide, samples were taken also at high tide. A one-litre sample of surface water was taken at about 20-cm depth, some 1 to 2 meters from the bank. Samples were analysed for somatic coliphage, E. coli, Salmonella spp.
and Enterococcus spp and helminth ova.
2.2.4 Aquatic spinach samples
In rural areas, aquatic spinach is usually planted in fishponds that receive PBD’s effluent. Spinach is commonly used for human as well as porcine consumption. Fifteen aquatic spinach samples (about 20 g per sample) were taken from 15 fishponds receiving PBD’s effluent in Phong Dien District (Figure 2.4). Samples were placed in sterile 500-ml Erlenmeyer-flasks. Fifty to one-hundred ml of distilled water was added and samples were shaken at 120 rpm for one hour before analysis. In addition, 15 spinach samples were taken from urban canals in Ninh Kieu District (Figure 2.4). All
samples were measured for dry matter, somatic coliphage, E. coli, Salmonella spp., and Enterococcus spp.
2.3 Physiochemical and microbiological analysis