CAZRI makes eco-friendly sewage treatment plant

Water Today

2 mins read

The Central Arid Zone Research Institute (CAZRI) has innovated an environment-friendly sewage treatment plant (STP) based on the principle of plant-microbe interactions, aiming to recycle 90% of the wastewater in the arid and semiarid regions of the country.

The STP is based on the principle of plant-microbe interactions. The experiment has taken place at the CAZRI campus as the current sewage wastewater discharged from the residential quarters of CAZRI is 1 lakh litre per day. The STP formed has been designed to treat 1 lakh litre of wastewater per day. The observations and findings are based on this plant which costs just Rs 15 lakh. Estimates say that the plant can help villagers with an additional source of water for irrigation.

“There are three main components of the plant — sewage inlet chamber, treatment chamber and treated water collection chamber,” said Rajesh Goyal, principal scientist (soil & water conservation engineer), CAZRI.

Untreated wastewater enters to the sewage inlet chamber at a pre-determined flow rate controlled by a V-notch, and in case of excess wastewater inflow, it returns to the collection chamber without treatment.

In the second stage, from the sewage collection chamber, the wastewater flows to the treatment chamber which consists of three zones — inlet zone (0.5 m), treatment zone (44 m) and outlet zone (0.5 m).

Explaining the most important and experimental part of the plant, Goyal says, “In the treatment zone, Typha and Napier grass is planted at 60x60 cm spacing. The microbial interaction plant creates a biological process which either removes or lowers down contaminants from the water. The surprising results of the process can be determined from the fact that Biological Oxygen Demand has been lowered from 30.6 mg/l to 6 mg/l. The water fit for drinking should have 5 mg/l or below.”

The untreated wastewater travels almost 45m before it enters into outlet zone after being treated. From the outlet zone, the treated water is collected in an underground tank of 1 lakh litre capacity. The treated water from the outlet tank is used to provide irrigation by drip system to Napier and other fodder crops. A detailed report on the biological process is under scientific examination and the research centre is not authorised to reveal it fully.

Other findings of the report include — Chemical Oxygen Demand (COD) lowered from 45 mg/l in untreated water to 8 mg/l.

The plant is eco-friendly as it does not require any energy for treatment of sewage water. The plant is suitable for peri-urban areas where sewage from the household can be drained outside the town and utilised for growing crops after the treatment. Estimates say that the plant can help villagers with an additional source of water for irrigation. The project is based on the premise that the total average per day water supply to each family is about 1,000 litre in the country. The latest estimates say that out of total daily water supply, about 80% is used for toilets and baths which drains as wastewater through sewage lines.

Disclaimer: This story has not been edited by Water Today staff and is generated from news feeds. Source: Times Of India.

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