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Basics of Liquid Waste Management-

What is Liquid Waste?

            Water ‘wasted’ as a result of various human activities at home, in businesses, or in industries is called liquid waste (LW). In other words, “Used & unwanted water generated during household or commercial activities is called Liquid Waste.”


What are the different types of Liquid Waste?

            Liquid waste or waste water generated in a human habitation can be classified as under.


Different types of liquid wastes have different characteristics -

    A) Grey Water

  1. Turbidity - Grey water is invariably turbid since it contains ash, mud, dirt etc.
  2. Oil and grease - Grey water from kitchen contains oils by which it becomes greasy.
  3. Organic matter - Grey water could contain organic matter since it carries kitchen waste and leftovers, it has higher BOD.
  4. Chemicals - Grey water can contain chemicals in the form of soaps and detergents used for t cleaning.
  5. Foul odor - On stagnation grey water emits foul odor due to decomposition of organic matter.

    B) Black Water

  1. High in organics.
  2. May contain pathogens since it is from the toilet and carries human excreta, urine and wash water.
  3. May emits foul odor

    C) Yellow Water

  1. May contain pathogens.
  2. Rich in nutrients.
  3. Foul odor – On stagnation emits characteristic ammoniacal odor.

    D) Community Waste Water

  1. It’s water that spills while collecting from public stand posts / handpumps.
  2. Could contain organics and chemicals, if the water point is used for cloth & utensil washing.
  3. If public stand posts/hand pump not paved, could carry dirt & mud .

    E) Commercial Waste Water

  1. The quantity and characteristics of this waste water depend upon the nature of commercial activity.
  2. The waste water from establishments such as industries & hospitals need to be treated as per existing laws & regulations. These wastes are not to be mixed with the household or community wastewater.

    F) Waste Water from Animal Shed :

  1. Waste water generated from urination of cattle head , washing of cattle shed and bathing of cattle . It is in the form of slurry containing particles from cow dung etc . Rich in nutrients but may clog sewer pipes soak pits if not treated properly before disposal .

    G) Storm Water :

  1. Waste water geberated during rain fall generally clean water but causes nuisance when it gets mixed up with grey water or other waste water . During rainy season storm water mixed with grey water causes stagnation and insanitary conditions in the villages . Villages ponds generally overflows during rains on account of storm water and cause flooding in low lying areas .

In most communities, household wastewater accounts for significant fraction of all wastewater generated in a village. Hence management of liquid waste in a village is synonymous to management of household wastewater.

How much waste water do we generate?

   Generation of waste water is directly proportional to the consumption of fresh water.

       As a rule of thumb 70 to 80 percent of the fresh water coming into a household goes out as waste water. Thus, if a household is receiving 400 lit of fresh water per day, waste water to an extent of 280-320 lit per day would be generated at the household. Similarly, if a village has a water supply tank of 20000 liter and the village is covered with piped water supply the wastewater generation of that village can be taken as 14000 - 16000 liter per day.

It is estimated that rural India generates about 15000 to 18000 million liters of waste water per day This estimate is on lower side

There is need to asses the waste water generation from cattle shed .Which is normally 30-50 lite per cattle head over and above domestic effluent .
In Peri urban areas or villages covered with piped water supply the aster water generation is higher as per capita water supply in such areas is in the range of 135-150 Litre per capita per day . Consequently domestic effluent ins such areas is @ 100-120 LPCD

Where does the waste water go?

   In rural areas, structured arrangement for the collection and treatment of waste water is very rarely found. The following trends are observed:

A) Gray Water : -

1) Indiscriminate disposal in the open
In majority of the villages a simple pipe or a drainfrom each house carries the grey water to a drain, nearby ditch or low lying areas.
2) Open or surface drainage system

A)
Faulty construction – Improper cross section, rough inner surface, cracks or leaks and improper gradient

B)
Misuse – disposal of household solid wastes blocks the drains resulting in stagnation and overflowing drains. Drains are also sometime used for defecation. All of which leads to unsightly and unhealthy

C)
No maintenance – Inadequate person power and financial resources results in poor maintenance of the drains.
3) Unscientific kitchen garden
More often than not, there is no planning for reuse of grey water in kitchen gardens. There is no thought given to the soil, plant type, quantity and characteristics of grey water. As a result, grey water accumulates in the courtyard and filthy and unhygienic conditions.
4) Unscientific soakage pits
Soakage pit is a simple and cost effective option for managing grey water. However, as they are not designed and constructed properly they function inefficiently and are unable to absorb grey water and it often overflows.

B) Black Water : -

1) Effluent from septic tank toilets
The effluent from septic tank toilets is either left in open or flown through open drains. Both the practices are not desirable as the wastewater are high in organics and pathogens and could pollute ground and surface water sources.

C) Yellow Water : -

1) Human Urine
In individual households, toilet is used for urination but at public places & in institutions like schools urinals are essential. In most cases such urinals either do not exist or are in a very bad condition and urine generally flows in the open or into open drains.

What are the consequences of this mismanagement?

  1. Unpleasant & dirty surroundings due to stagnation of grey water
  2. Health implications-
    Although grey water does not contain pathogens, stagnation could lead to vector and especially mosquito breeding resulting in endemic diseases such as malaria, filaria, encephalitis etc. Since black water from septic tank and toilets contain pathogens poor management could lead to the spread of diseases.
  3. Pollution / contamination of water bodies
    Indiscriminate disposal of waste water results in contamination of water bodies such as river or pond. Many times the constructed drains also end up in water bodies and pollutes these natural resources.
  4. Wastage of precious natural resource – The Water
    Waste water needs to be seen as a resource and with growing water shortages recycle and reuse of wastewater should be encouraged. This can save huge quantity of fresh water.