Bangladesh – Water and Sanitation

Imagine an environment that has an extremely high water table, is very flat, has huge rainfall and you have to build a toilet and wash area that not only removes waste but treats it so that it is safe for the surrounding community and your family…your budget is minimal.
This was our brief.

Project Background septic tank trials since 2013

HLPS Targeted

This project targets HLP1 washing people, HLP2 washing clothes and bedding, and HLP3 removal of human waste safely. The high water table means that a well built and detailed waste treatment system is critical to on-going health improvements.

 

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8 toilet and septic systems built

The two trial septic systems were monitored and found to treat wastewater effectively in the high water table environment.

The value of testing prototypes allows a better understanding of local materials, construction, skills and environmental conditions. Treating wastewater is a serious problem that if not properly designed and constructed will lead to poor health. The trail and evaluation of the septic tanks was a success and now is beginning to be rolled out through the community.

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A Case Study Trial of two septic tanks

The two types of septic tanks being trialled, (the brick rectangular system and the concrete ring system) still under construction and surrounded by mud.

Human waste contaminating water. Waterborne illness and gut infections

Measure the amount of wastewater generated

Develop two designs for septic tanks with waste quantity, local skills, knowledge and communities.

Ensure septic systems are sealed from groundwater

Build trial systems and monitor function

Complete eradication of E. coli at water pump points

Lessons from the Data Does our work effect health?

After the installation of septic tanks, the E.coli readings were dramatically lowered at both water pumps and effluent discharge points

E.Coli is an indicator of fecal contamination in freshwater. This is associated with an increased risk of gastrointestinal illness and respiratory illness. It can cause illness and in rarer cases chronic illness and even death.

Community water

>1600

Septic discharge

>200

E.coli readings at community water sources (school playgrounds, rice fields, standing water pools by the roadways) were dangerously high.

After the trial of septic tanks, the E.coli levels were radically lowered even at the discharge point for the septic tank.

Community water

>1600

Water pump

0

E.coli readings at community water sources (school playgrounds, rice fields, standing water pools by the roadways) were dangerously high.

Through the trial of septic tanks, the E.coli levels at the water pump were eradicated.

Design Solutions Examples of Key Design Initiatives

2014 Water Innovation Challenge

Looking back to the inaugural Water Innovation Challenge in 2014 which had two multidisciplinary teams aiming to design a toilet that removes waste safely for Bangladesh. Healthabitat acknowledges the skill and effort contained in the sanitation design ideas presented by both Team USA and Team Australia in Singapore. Below is Healthabitat’s feedback on each design, the following comments are intended to inform and prompt more thought from the teams and those interested in this area of work. HH has chosen to comment on the Bangladesh design work only at this stage (schemes for Nepal were also presented).

We invite further comment and discussion through the website.
Sincere thanks to all those involved in the teams, support staff and home town research and development specialists.

You can download the complete project reports.

8 toilet and septic systems built
Team USA's solution for the 2014 Water Innovation Challenge. Note the raised toilet for proper drainage.

Thoughts on Team USA

  1. The solution does collect human waste from the ground and separate it from the water table,
  2. the scale of the digesters appears far too large for the number of people served, building the volumes involved will incur a high construction cost and would require large volumes of waste and time to generate gas pressure,
  3. the digesters will occupy a large area of land and poor villagers have little land – the idea presented that people could live above the digesters is a good one – but still, a large area of productive agricultural land is lost,
  4. there was no clear way indicated to remove the final waste product from the digesters, the hatch idea suggested in the final presentation would release gas and tanks would need to be isolated, the waste would accumulate in all the tanks so many hatches would be needed,
  5. the dual pipe interconnection between all the tanks implies the waste is liquid enough to flow between the tanks and this would mean no progressive treatment over time, solid waste would start settling in the first tanks but would have ‘new’ waste flooding over it constantly,
  6. solid waste would settle in the first few tanks, and progressively all the tanks, and they all would require access for cleaning,
  7. the height of the toilet building could be reduced without impact on the current design and make the access and hand wash water pumping lower, easier and less costly to construct,
  8. Privacy issues, particularly for young women, when villagers are seen to be ‘ascending the stairs’ to the toilet
  9. the bamboo of the toilet building walls would need better weather protection (with the roof or render) to prevent decay,
  10. the columns that run into the ground would decay (if they are timber as indicated in parts of the specification),
  11. is there a great health need for biogas in Bangladesh? Cooking is usually done in a well ventilated outside, roofed place,
  12. the detailing of the toilet area (wall surfaces, floor wall junctions, grading of the floor) must consider the high prevalence of gut problems and diarrhoea by making sure it is easy to clean the inside of the cubicle to at least to 900mm (3’) from the floor. The bamboo lining to the inside walls will be hard to clean.
  13. Ensure all the cleaning water is drained from the unit and safely treated and does not escape untreated to the outside ground.
8 toilet and septic systems built
Team Australia's Solution 2014 Water Innovation Challenge. Note: the separation of solid and liquid waste.

Thoughts on Team Australia

  1. The solution collects human waste,
  2. the separation of liquid and solid waste at source (as indicated in the diagrams) will not guarantee that the liquid waste is uncontaminated. Therefore,the release of this liquid directly into the reed bed / pond remains a real health hazard,
  3. the local custom of using water for washing after toileting will further, regularly contaminate the liquid waste stream with solid waste and if this liquid stream is not treated it will greatly increase the health hazard,
  4. the ability to flood or dilute the pond / reed bed (either by adding stored water OR rain water) will not improve the water quality it will simply spread more contaminated water further,
  5. the reed bed system will not treat waste, rather is will remove excess nutrients from treated waste water and this treatment needs to be incorporated into the design,
  6. ultra violet light (from sunlight) could have a sterilising effects on the pond / reed bed water if it were shallow BUT during the wet season, when the problem of contaminated water is greatest, cloud cover will limit the available daily sunlight, the reeds also limit the impact of UV radiation by shading the water,
  7. the scale / footprint of the toilet unit could be reduced, it will occupy an area of land that could be used for agriculture – poor villagers have little land,
  8. the communal nature of the unit will need a high level of village management and the proximity of houses and families may make this design unworkable, think about who will maintain the unit and be responsible for daily cleaning and maintenance and will they be paid?
  9. if the whole unit provides only one working toilet place (as the other 3 are resting the waste material) the total number of people served will need careful consideration, particularly if it is a communal toilet,
  10. the costings are not accurate and items noted in the specification are not included (or cannot be identified in the costing)
  11. a hand washing point is essential as a third of the health gain from having access to a working toilet comes from adequate hand washing being close to the toilet,
  12. the detailing of the toilet area should acknowledge the high prevalence of gut problems and diarrhoea by making sure it is easy to clean and all cleaning water is safely treated and does not escape to the grounds surface.

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