Oceanides Global Solutions LLP

Understanding Residential Wastewater


Courtesy of Oceanides Global Solutions LLP

Urban areas are the biggest culprits when it comes to waste generation. Most of Indias waste comes from cities and towns. With municipal STP clearly inadequate in handling the massive amounts of wastes produced, there is an urgent need to decentralise waste management in India. The beginning has been made with many State governments now considering compulsory STPs in residential complexes.


With focus now shifting to waste management at residential level, STP plants manufacturers India are now building plants that are suitable for the cramped space of a residential complex. As laws are expected to tighten further, it is important to understand what it entails, what kind of waste is generated in a residential complexes and how we can best manage this. We must also recognise the challenges that we can face and how to meet these.


Wastewater in a Residential Complexes


Wastewater is what we get when we use fresh water in our everyday usage, including cooking, cleaning, bathing, washing vegetables and clothes. This wastewater is typically of two types: grey water and black water. Grey water is the wastewater that we generate through activities like bathing, washing vegetables etc. Black water or sewage is the wastewater that is flushed down the toilet with excreta.


Grey water is contains waste like vegetable matter, oil, grease, detergent and dirt, whereas black water is much more toxic. This is why grey water is easier to treat. Treating sewage requires more resources and time. However, in India there is rarely any segregation of the two wastes from residential complexes. Both the waste are carried through the same pipes.


If we further study wastewater, we can further break down its composition. Some of the minerals that were already present in the freshwater will also be found in wastewater. In addition, it will have added matter, which when seen as when seen in its composition is oils, protein and carbohydrates.


These are biodegradable waste and can be broken down through oxygen. Their treatment is, hence, measured in terms of the oxygen that will be required to treat the waste, known as Bio Degradable Oxygen demand(BOD). However, not everything is biological. There are also some chemicals that are generated in our day to day waste which is degradable. The measurement here is known as Chemical Oxygen demand (COD). So, STP plants manufacturers India often express a plant capacity in terms of its COD and BOD levels.

Sewage or black water has certain additional elements that stay on and can be extremely dangerous. These include harmful bacteria like e.coli. It can also turn septic very quickly and develop an unpleasant odour.


Wastewater Quantity


The question here is how much wastewater is generated in a residential complex. As per Central Public Health Environmental & Engineering Organisation, the average fresh water consumption per person lies between 135 and 150 litres per day. Considering that almost all of it turns into waste, we can take this as the measurement of wastewater produced per person per day. So, the calculation for wastewater produced in one residential complex is simply no of people X 135 litres.


But this is at the lowest range of consumption. Modern living conditions has actually increased the level of water we use. An automatic washing machine, for instance, uses immense amount of water. Similarly showers, modern flushes all demand a massive amount of water, which drives up the amount of wastewater we generate.


Without an STP at local level, all this wastewater flows into already overburdened municipal STPs.


Need for separation of wastewater


As explained above, grey water is much easier to treat than black water. It can aerated and then treated by coagulants and filtration. The treated water can be reused in many ways. Black water, on the other hand, needs a more intensive process. In general, grey water treatment plant requires less resources and is hence, cheaper, quicker and less likely to malfunction. However, most STP plants manufacturers India are asked to combine great and black water treatment because of space constraints.


The government is now looking for more stringent measures and mulling separation of waste pipes. With modern STP plants manufacturers India now equipped for a wide range of waste treatment, we need to evaluate our methods of local wastewater management. 

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