Frequently Asked Question

1. What is Waste Water? How is it generated?

Waste water is the water that emerges after fresh water is used by human beings for domestic, commercial and industrial use. This document will restrict itself only to the waste water generated due to domestic use.

By and large,it is fresh water that is used for a variety of domestic uses such as washing, bathing & flushing toilets. Washing involves the washing of utensils used in cooking, washing vegetables and other food items, bathing, washing hands, washing clothes.

The water that emerges after these uses contains, vegetable matter, oils used in cooking, oil in hair, detergents, dirt from floors that have been washed , soap used in bathing along with oils/greases washed from the human body. This water is referred to as “ Grey Water” or sullage.

Water used to flush toilets to evacuate human excreta is called “ Black Water” or Sewage.

Grey water is easier to purify as compared to black water, i.e sewage. However, the practice predominantly followed in India is to combine these two wastes to discharge into a public sewer or into a sewage treatment plant in a residential community/ building that has no access to a public sewer.

  • The sizing [model (pore size) and dimension] of Geotube for plant capacities.
    • Sizes ranging from 11m3, 90m3 and 160m3 or to tailor made any sizes to suit the waste sludge require. The difference is only the quantity utilise, bigger plant capacities require more bags. (Depend on area provided)
  • Factors to be taken into consideration to enable Geotube to be ideally installed at STP site (i.e. drying bed space, site surrounding, availability of sludge holding tanks, etc.).
    • Facility such as sand drying bed or a flat concrete place with proper drainage system require to lay a Geotube.
    • Sludge from Sludge Holding tanks can be transferred to Geotube for the purpose of desludging directly.
  • Under normal operating condition, cost involved for:
    • Complete initial installation (Geotube, dosing pump, piping, consumables, labour etc.)
      • Dosing pump, piping is already available in the existing STP as such no additional equipment is required.
    • Operation (electricity, labour, pump maintenance, lab testing, polymer, disposal of Geotube etc.)
      • Cost of disposal of sludge is cheaper compare to only using sand drying bed because Geotube does not require sand replacement. However, polymer is used for better result and clearer filtrate.
    • Replacement of Geotube (complete installation)
      • Replacement of Geotube is easy as it only need to place on the sand drying bed without any accessories and additional manpower.