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Sanitation and Biogas Technology in Rural Areas: A Comprehensive Guide, Study notes of Environmental Engineering

sewage and waste water treatment

Typology: Study notes

2019/2020

Uploaded on 01/09/2020

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5. RURAL SANITATION
INTRODUCTION
Rural area : Settled places outside towns and cities
Most of villages not yet provided with protected water supply systems
Villages depend on near by available sources
The sources are polluted with human activities like
a) Bathing
b) Washing of cloths
c) Swimming
d) Cleaning animals etc
If not protected properly, people get waterborne diseases like
Typhoid
dysentery
Cholera
Jaundice etc.
Improvements of the sources are to be done to avoid health hazards
Available water sources
1. Wells
2. Ponds
3. Streams
Precautions to be taken for protection of water sources
) Wells :
Stepped wells :
a) Stop people get down and bring water
b) Arrange to lift water with
i) Rope and Bucket
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5. RURAL SANITATION

INTRODUCTION

Rural area : Settled places outside towns and cities

  • Most of villages not yet provided with protected water supply systems
  • Villages depend on near by available sources
  • The sources are polluted with human activities like a) Bathing b) Washing of cloths c) Swimming d) Cleaning animals etc
  • If not protected properly, people get waterborne diseases like
  • Typhoid
  • dysentery
  • Cholera
  • Jaundice etc.
  • Improvements of the sources are to be done to avoid health hazards Available water sources
  1. Wells
  2. Ponds
  3. Streams Precautions to be taken for protection of water sources ) Wells : Stepped wells : a) Stop people get down and bring water b) Arrange to lift water with i) Rope and Bucket

ii) Pumps or iii) Wind mills c) Avoid individual bucket and rope carrying d) As for as possible this source is to be avoided for rural water supply 2)Ponds: Practices like i) Bathing ii) Washing cloths iii) Cleaning cattle etc. Should be stopped b) Watchman can be arranged to stop the above activities c) Water can be pumped, disinfected and supplied to people.

  1. Streams :
    • Water can be pumped, disinfected and supplied to people
    • Proper education should be given to villagers about a) Need for protected water b) Waterborne diseases. sanitation is required
    • To maintain good health
    • Personal health depends on community health What is to be done to have sanitation in rural areas?
    • Education about health and hygiene
    • Proper collection, transportation and disposal of liquid and solid wastes Sanitation a) The hygienic and safe way of
      • Utility of Sanitary fixtures
  • Leads to occurrence of hookworm disease to the people accustomed to open defecation without footwear Remedy: Construct and use at least Sanitary latrines to deal human excreta
  1. Indiscriminate throw of solid wastes
  • Causes insanitary conditions
  • Fly nuisance is more
  • Spread of diseases is more Remedy: Dispose solid wastes by sanitary landfill or composting
  1. Use of artificial fertilizers
  • Contaminate water sources
  • Contaminate soil
  • Contaminate crops if dosages are more Remedy: Discourage use of artificial fertilizers and encourage the use of bio-manures
  1. Lack of education on Environment
  • Leads to maintain poor environmental conditions Remedy: Educate to eradicate ignorance, illiteracy, superstitions, and to successfully maintain healthy environment in rural areas Rural Latrines
  1. Pit privy
  2. Bore - hole privy
  3. Aqua privy
  4. Cesspools etc
  5. Pit Privy
  • The pit size is 1.2 x 1.2 x 1.5 m
  • A squatting seat is provided at top of the pit
  • Seat is covered with a wooden cover which can be kept closed when not in use
  • A temporary structure is constructed over the pit
  1. Sides are sometimes lined with wooden planks or GI sheets
  2. A vent pipe is provided to allow foul gases to escape
  3. When the pit is filled, it is closed with 60cm thick earth layer
  4. New pit is excavated by the side of it
  5. The temporary structure is shifted to the new pit
  6. After each use a little earth is thrown into the pit
  7. Lime is applied frequently to reduce the bad odour
  8. The pit privy should be atleast 30m away from existing well to avoid water pollution
  9. This can be adopted only if water table is low, no surface drainage is admitted into the pit
  10. Bore-hole privy :
  • It is similar to pit privy, except that instead a pit, a hole of 300 mm to 400 mm diameter is drilled with an auger
  • The depth on hole is 4 to 8 m
  • The bottom of hole should be atleast 1 m above water table and may be 4 - 8 m deep
  • It is an improved latrine as shown in the figure
  • The hole is drilled outside the compartment
  • To avoid bad odour a trap with water seal may be provided
  • When the hole is filled, it is closed with thick earth layer
  • New hole is excavated by the side of it
  • The method is suitable for sandy soil areas
  • The method avoids fly nuisance and bad odour Aqua Privy / Wet latrine
  • It is permanent type
  • It is based on the principle of septic tank
  • It consists of a chamber for anaerobic digestion and a soak pit
  • Latrine pan is fixed on the top of chamber and the drop pipe attached it is dipped into liquid
  • Fruits and vegetable wastes
  • Kitchen and dining hall wastes
  • Agro-processing waste or effluent
  • Crop wastes
  • Bio-gas :
    • Fuel gas produced with the organic waste from living things
  • Bio-gas plant :
  • A container where the organic waste is digested to produce the fuel gas
  • Biogas technology provides an alternate source of energy in rural India
  • It is an appropriate technology that meets the basic need for cooking fuel in

rural areas

  • Using local resources, viz. cattle waste and other organic wastes, energy and

manure are derived

  • The anaerobic digestion of biomass leads to the production of the combustible

gas methane.

  • Methane - 60% and Carbondioxide - 39% are the two products obtained from

biogas plant

  • The calorific value of biogas depends on the amount of methane gas present

in it

  • Anaerobic digestion is a process in which microorganisms break down biodegradable material in the absence of dissolved oxygen
  • Anaerobic digestion produces methane rich biogas, suitable for energy production
  • Also, the nutrient-rich solids left after digestion can be used as fertilizer
  • The three stages of in the process of biogas production are :
    • Hydrolysis

Principles of Biogas Production

  • Acidification or acid formation
  • Gasification or methane formation
  1. Hydrolysis :
  • In this stage, complex substances are converted is to soluble carbohydrates
  • Through hydrolysis anaerobic bacteria break down organic matter into simple sugars, amino acids, and fatty acids.
  1. Acid formation & Acidification :
  • In this stage soluble oragamic compounds are converted into volatile fatly acids by anaerobic and facultative bacteria
  1. Methane formation or gasification : It this stage the soluble acids are converted into methane and carbon dioxide by the methenogenic bacteria
  • This bacteria is sensitive to both high and low pH’s and occurs between pH 6.5 and pH 8 Factors affecting biogas production
  1. Influent Solids Content
  2. Seeding
  3. pH
  4. Temperature
  5. Nutrients
  6. Toxic Materials
  7. Stirring
  8. Quality of raw materials 1.Influent Solids Content
  9. Production of biogas is inefficient if fermentation materials are too dilute or too concentrated
  10. Optimum gas production is obtained with 1:1 slurry of cow dung and water.
  11. Seeding
  • Government of India launched ‘National Biogas Programme’ countrywide through Ministry of Non- conventional Energy Sources In 1982 Some biogas plants recognized by MNES (Ministry of Non-Conventional Energy Sources)
  1. Floating-drum plant with a cylinder digester (KVIC model)
  2. Fixed-dome plant with a brick reinforced, moulded dome (Janata model)
  3. Floating-drum plant with a hemisphere digester (Pragati model). Construction of KVIC model
  • It consists of a circular tank with brick masonry in C.M. 1:4 on C.C. floor
  • Inside of the tank is plastered with CM 1 : 3
  • The tank acts as an anaerobic digester
  • It is divided into 2 parts by a vertical partition wall
  • A steel gas holding dome placed on the top of digester
  • It is provided with an inlet tank and out let tank connected by AC inlet and outlet pipes
  • The steel dome rests on a beam when there is no gas in it and floats in the slurry when gas is accumulated Working of KVIC model
  • Cow dung and water mixed in the ratio of 1 : 1
  • The slurry is fed into the digester through inlet tank
  • The slurry slowly passes through inlet pipe, digester and outlet pipe
  • Detention time for the digester is 55 days
  • During that period, the slurry is digested and aerobically and biogas is produced
  • The accumulated gas can be taken to the kitchen through a pipe
  • Daily, a volume of slurry equal to that fed inside is drawn out through outlet chamber Construction of Janata model
  • It can be completely constructed with locally available materials like bricks, cement, sand etc
  • Steel is not used any where in the construction
  • It has a circular masonry tank constructed on concrete floor
  • It is provided with a dome shaped fixed roof constructed with bricks and cement mortar
  • The entire structure remains below the ground level
  • At the middle of the depth, two rectangular openings are provided connecting the adjacent inlet and outlet chambers Working of Janata model
  • Cow dung and water are mixed in the ratio of 1 : 1
  • The digester is fed with slurry to a level above inlet and outlet doors
  • Every day dung slurry is fed through inlet chamber and an equal quantity can be withdrawn from outlet chamber
  • Detention time collected into the dome position can be draw to the kitchen through a pipe Advantages of Biogas plants 1.Provides a renewable fuel source 2.Ground water pollution is prevented 3.Handling and disposal of digested sludge is easy 4.Digested sludge can be used as manure 5.Consumes methane that might otherwise leak into the atmosphere and increase the greenhouse effect.
  1. Pathogenic organisms are destroyed
  2. House fly and mosquito breeding is eliminated
  3. Destruction of weed seeds present in the dung
  4. Esthetic value of surroundings improved by the disposal of waster through these plants Disadvantages of Biogas plants
  5. The main disadvantage is the loss of the organic waste for compost or fertilizer
  6. Very limited quantity of electricity can produced on on the global scale
  7. There is little or no control on the rate of gas production, although the gas can, to some extent be stored and used as required