Question

What are the various challenges in designing a wastewater treatment plant? Provide, at least three, and a way to address these challenges.

Answer 1

There are various problems associated with designing of waste water treatment plants.

Three of them are listed below along with a solution to overcome them:-

1. Requirement of large volume of aeration tanks:-

As the primary and major impurities of sewage is organic matter which may be either biodegradable or non biodegradable are to be digested or decomposed by aerobic or anaerobic micro organisms. If the waste water is used to be treated aerobically it requires large volume of aeration tanks to provide oxygen for the action of aerobic micro organisms. And it may be possible that there may be shortage of land for providing such a large aeration tanks.

Remedy:- in such condition chemical coagulants may be used which brings the particles closer and it reduces the amount of area required for the aeration tanks.

2. Consumption of large amount of energy:-

As we know organic matter is the primary impurities present in the waste water. So in order to remove them aerobically large amount of oxygen is required which can not be governed naturally as natural process may be time consuming. So aerators are used to provide oxygen artificially to facilitate the aerobic micro organisms which incur huge costs as they require external energy source to run them.

Remedy:- In order to reduce the energy consumption instead of going aerobically one can opt for anaerobic decomposition which is little bit slower than aerobic but cost will be much lesser than the former and one more advantage is that dead cell mass of micro organisms will be less in case of anaerobic micro organisms which further reduce the cost of dewatering the sludge which is major problem associated with aerobic decomposition.

3. Environmental impact :-

As the waste water contain organic matter along with it also contain some heavy metals, oil and grease particles, toxic impurities etc. Which are harmful for micro organisms (which are most essential for waste water treatment) may inhibits their growth makes waste water untreated completely or partially treated which if disposed in water bodies may pollute the water body and leads to deficit in dissolved oxygen in the water bodies which hampers the life of aquatic species and also due to the presence of pathogenic micro organisms it may cause dangerous desease to human beings if used for drinking purposes.

Remedy:- proper and sequential treatment like oil and grease particles must be removed by skimming tanks, heavy and toxic metals must be screened and processed properly and if possible opt for landfilling or effluent irrigation or deep well injection etc. instead of polluting water bodies.

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