Patent Reflections: A Solution for Sewage Treatment

Why Is This Invention Important?

Today, we can see the problem of drinking water has popped up in various parts of the world. We can even see international relations getting strained in Africa because of water scarcity. To cope with this problem, various nation states are taking steps towards water conservation and recycling using water treatment plants. This process involves cooperation at political, social and academic levels.

In today’s Patent Reflections, we are going to look at a patent granted in 2021. Titled Sewage Treatment Plant System (Indian Patent Application no.  202141014698 A), it is an innovation of the civil engineering department at Lords Institute of Engineering and Technology, Telangana.

The Invention

image of interconnected chambers making up the sewage system

Keeping in mind how India’s infrastructure facilities are not evenly distributed, this invention focuses on the situation when remote or rural areas do not have ready access to municipal waste water treatment plants. Other communities who might lack access to WWTP may include isolated habitats, military outposts, remote agricultural or industrial operations etc. This invention is geared specifically to help out those in this situation. The ultimate aim of this invention is to increase the self-sufficiency of these communities when it comes to water treatment.

A wide range of liquid waste is generated in communities. These include sewage water, grey water, black water, oily water, and other organic and inorganic impurities. The sewage treatment plant in the present invention consists of a series of chambers such as screening chamber, grit chamber, skimming chamber, primary sedimentation chamber, aeration chamber, secondary sedimentation chamber, filtration chamber and disinfection chamber. All these chambers are connected with each other by fluid communication. The treated water can be used for agricultural as well as potable purposes.

Screening is a process for raw sewage passing so through two different screens, made up of small diameter steel bars to remove small and large floating material such as leaves, paper, timber pieces, rags, sanitary waste, etc. In short, materials that can damage the sewage treatment plant are removed first. This screen can be both manually and mechanically operated.

The grit chamber contains ferric chloride that removes the materials having a particular type of specific gravity that is more than 2.65 such as sand, gravel and other materials that can clog the sewage chamber. The grit tank is a continuous flowing tank where materials with particular specific gravity settle down and rest flow.

The skimming chamber removes oil and grease before the water reaches to sedimentation chamber. Oil and grease is removed by scouring using skimmers. This chamber contains an outlet at the bottom from where oil and grease trapped in skimmer is removed with the help of a submerged stirrer.

The water then goes to a pre settling basin (primary sedimentation chamber), which is a large tank underground. Here, the sludge gets settled after the removal of oil, grease and wax. Now particles with specific gravity for less than 2.65 are removed using alum and ferric chloride.

The water is then lifted to an aeration chamber using a motor with suitable horsepower. In this chamber, air is circulated using submerged aerators mixed with a liquid or substance. This chamber is responsible for biological treatment of water where organic and colloidal contaminants are broken down using microbes. Chlorinated compounds are also removed in this chamber.

After this, water is lifted to secondary sedimentation chamber where a layer of alum and ferric chloride helps to remove the scum. After the removal of scum the water becomes capable of being used partially or fully for agricultural purposes.

The water may them be taken to filtration chamber. Here, physical, biological and chemical operations occurs where solids and fluids are separated using various filter mediums such as locally available coarse aggregate and fine aggregate. Then water is disinfected using calcium hypochlorite that is used to kill calcium microbes. This now allows the water to be used for human needs.

Economic Feasibility

As with all inventions, getting an idea into a workable format is only the first step. The second is implementing it. This invention is clearly a boon for an increasingly water scarce world, and it’s clear that there needs to be further research done into more effective and efficient ways of waste management. In addition, there can be claims made of the construction system using locally available materials and generating employment in areas where work is also scarce.

However, there seem to be some basic infrastructural and cultural barriers to wide-scale implementation of this solution. At the outset, this plant looks like it requires quite a lot of both space and energy, both of which are limited in today’s India. This is particularly so in the rural areas the treatment plant is supposed to cater to, as the clearing of forest cover and agricultural land is an ongoing problem.

More importantly, India is a culture historically obsessed with cleanliness. It persists today in the rigors of the caste system, where many of the lowest classes are assigned the work of cleaning all the waste everyone finds disgusting or unappealing. It’s likely that there will be staunch resistance to the usage of recycled sewage water in some communities, regardless of how chemically pure it technically will be.

Author: Tushar Srivastava, Intern at PA Legal.

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