1. DESCRIBE AND EXPLAIN THE TREATMENT MECHANISMS IN BVIPS AND PIT LATRINES WHERE THEY ARE USED SITING TREATMENT MECHANISM OPERATION AND MANTAINANCE

2. NAMESTUDENT NUMBER BEKEZELA MOYON0176125E HERBERT KAZONDAN0176167W WEDDINGTON MATANGAN01417717B CLETO MUCHEMWAN0176152K VIVIAN MUNASIN0176117D RONALD CHIGAUN0176127G CONRAD KAMUTANDEN0176151J

3. INTRODUCTION The BVIP Latrines has been Zimbabwe’s only standard official technology of choice for rural, peri-urban since1975. (Peter Morgan).

4. INTRODUCTION PIT LATRINE a type of toilet that collects human waste in a hole in the ground. BVIP is an improvement on the pit latrine (Peter Morgan,) on the following: i. Continuous air flow through the ventilation pipe ii. Preventing odour iii. Trapping of flies as they try to escape through the light

5. PIT LATRINE AND BVIP CROSS SECTION

6. PIT LATRINES A pit latrine is a simple and inexpensive toilet, minimally defined as a hole (pit) in the ground. More sophisticated pit latrines may include a floor plate. A pit is typically sited well away from any water sources to minimize possible contamination. After prolonged use, a pit is typically buried.

7. PIT LATRINE This consists of a slab over a pit which may be 2 m or more in depth. The slab should be firmly supported on all sides and raised above the surrounding ground so that surface water cannot enter the pit. If the sides of the pit are liable to collapse they should be lined. A squat hole in the slab or a seat is provided so that the excrete fall directly into the pit.

8. PIT LATRINE The pit latrine has no provision of ventilation and trapping of flies. Gases produced are released through the squating hole Flies gain entrance and exit of the pit through the squating hole Anaerobic decomposition and emission of methane gas.

9. The Blair Ventilated Improved Pit (BVIP) Latrine The BVIP toilet system design: has features to enhance sanitation and health aspects of pit toilets These features are promoted naturally by:  wind,  sunlight and  natural decomposition processes.

10. RURAL SANITATION TECHNOLOGY OF CHOICE

11. SITING THE BVIP & PIT LATRINE The site should be chosen by the family with technical advice from the EHT and the following should be considered:  A distance of at least 30-50m away from the water sources to reduce possible underground contamination of the groundwater through seepage  should be accessible at least 20metres from the dwellings

12. SITING THE BVIP & PIT LATRINE  Should be at the leeward direction from houses and should face windward side.  On slightly raised ground – so that rainwater can drain away from the site of the toilet  where the soil is firm to avoid possible latrine collapse  The orientation of the structure - to provide the best privacy for the users

13. THE PRINCIPLE OF THE BVIP SYSTEM 1. Structural Design floor slab has 2 holes – o Squat hole + Vent hole & superstructure Semi darkness. Can be built as a single, double or multi-compartment structure 2. Excreta and anal cleansing material drops into the pit where the organic material decomposes and excess liquids percolate into the surrounding soil. 3. Air flow BVIP system produces a continuous airflow through the squat hole, escaping through the ventilation pipe.

14. TREATMENT MECHANISMS OF BVIPS Aerobic decomposition is faster but does not reduce the volume of sludge as much as anaerobic decomposition does. Sludge decomposes in one of two ways; aerobic or anaerobic. Inside a typical pit there is a fairly small zone of aerobic activity near the surface while the rest is anaerobic. Micro-organisms that do the work of degradation are already present in faeces, no need for artificial additives to enhance the process.

15. TREATMENT MECHANISMS OF BVIPS Typically 30% of the dry mass of faeces is made up of bacteria and 80% can be considered biodegradable. 70- 80% of wet sludge is made up of water. Over time in the pit biodegradable organics generally degrade, dissolved components leach out, whilst sand and rubbish remains unchanged.

16. ADVANTAGES AND DISADVANTAGES Advantages of a BVIPDisadvantages of a BVIP 1. Can be built and repaired with locally available materials Flies and odours are normally noticeable 2. Low (but variable) capital costs depending on materials and pit depth Low reduction in BOD and pathogens with possible contamination of under groundwater 3. Small land area requiredCosts to empty may be significant compared to capital costs 4. Flies and odours are significantly reduced (compared to non-ventilated pits) Sludge requires secondary treatment and/or appropriate discharge

17. Advantages of a pit latrineDisadvantages of a pit latrine 1 Can be built using locally available materials at a low cost Nuisance from flies and mosquitoes (and sometimes cockroaches), and bad odours

18. FACTOR AFFECTING DECOMPOSITION IN BVIP & PIT LATRINES Temp- the optimum temperature for improving faeces biodegradability is within the thermophilic range of 60°C, but at 70 °C the activity of biomass is very low due to diminishing enzymatic activity (high temp) pH- appropriate pH is within a range of 6.8-8, if it is below or close to 6 the sensitivity methanogenic bacteria are inhibited and starts to die. Characteristics of the surrounding soil- the porosity of the soil will determine the leaching and draining process that will occur in the pit.

19. THE CURE FOR OVERLOADED PIT LATRINES, BVIPs A Biological Activator Remedy for a Biological Problem There are a number of factors which influence the correct functioning of a pit latrine, e.g.. 1. the depth and width of the pit, a high water table in that area, 2. the use of chemicals to control odour etc 3. also the use of materials other than toilet paper (cement packets, sticks, stones, etc!) for sanitation purposes. Bio-Effector is a bioremediation product that rapidly promotes microbial activity in anaerobic and aerobic environments.

20. MAINTENANCE Pouring of water through the vent pipe to deal with dead flies and cob webs, in the case of bull nose. Replacement of the damaged fly screen in the case of a doom shaped vent tip. Minimal use of detergents for cleaning purposes to promote biological treatment processes.

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