Difference between revisions of "Team:IIT Kanpur/Human Practices"

Naturally human waste takes around 4-5 days to completely decompose. Nowadays sewage is treated in plants where it takes about 4-5 hours to degrade. To understand better how water from households is cleaned, we organized an industry visit to Unique water industries in Kanpur.
After an in depth conversation with the company official, it became clear that biological processes are at the heart of almost every sewage treatment process. The industry which we visited uses a technique called RBC (Rotating biological contactor)
This plant uses a 3-Rotor model for RBC. The first rotor introduces the bacteria into the sewage and aerates the sewage. Thereafter, the sewage is fed to a second chamber where the second rotor carries out the main aerobic reaction, where bacteria degrades . Maximum time is spent in the second chamber where the majority of the cleaning takes place. Eventually the third rotor removes dead bacteria from the water, after which the treated water is collected based on laminar flow. This water is fit for use in basic horticulture.
Other methods include sequential batch reactor, MBBR(Moving bed biofilm reactor) etc. There are issues regarding the complex procedure and huge amount of energy required to mix semi solid sludge. RBC is the simple to install and has low maintenance costs.
From our experiments we found out that the presence of (%) SDS reduces growth of E.Coli. Treating water for SDS before feeding to the RBC may improve the efficiency of the water that the RBC currently provides.
One more chamber can be connected where the first rotor is coated with the SDS-a protein obtained by the extracellular expression which will degrade the SDS in the primary discharge. Such subtle changes can bring out a drastic improvement in the water purification techniques, especially when dealing with SDS-Rich discharges from Hotel and Hospital discharges. The SDS concentration in such discharges reaches 8-9% which is difficult to neutralize even using chemical processes. Such an improvement can lead to a more efficient way of dealing high SDS content discharges using the RBC technique.

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As an academic venture, our team felt that discussing our ideas with fellow academicians would contribute to the growth of our project and also help us from pursue new lines of thought that we had not yet explored. To address this we felt that experts with knowledge on both environmental engineering and experience in practical implementations would be of great value.
We met with Dr. Purnendu Bose who is a Professor at the Dept. of Civil Engineering at IIT Kanpur and he specializes in environmental engineering. Our discussion was a fruitful exchange where we introduced our project about how we plan to clean detergent-laden water. We were unclear of any useful implementations.
He told us about the current problem faced by companies making Washing machines. People who are the target customers for these companies have the money to afford washing machines, but they still do not get personal washing machines due to lack of availability of clean water. He then suggested that we can model our product along the lines of this problem. It proved to be a crucial piece of information, and the whole conversation proceeded to ideate a washing machine add-on that recycles the water that it uses, and hence the water requirement for the washing machine decreases a lot. This model could be used generally to cut water wastage at a significant rate.

We met Dr. Rajiv Sinha who is also a Professor at the Dept. of Civil Engg. His expertise lies in Bioremediation, and his advice and suggestions were very helpful to us. Our problem was that though we had some idea of how our bacteria would work in the controlled settings of our lab, we did not know what challenges we would face when applying the same to water samples from the real world. One particular problem we had was that our enzyme might not work in the pH conditions, the presence of other ions etc. and so to understand real-world challenges we shared this problem with him.
He suggested that we test our protein’s function on SDS in the presence of major ions in water and see the concentration's effect on protein function. He guided us to check protein functionality with each of the major ions separately, to better assess the effects of each ion individually. We could then see the level of these prominent ions in water bodies in different places and formulate our strategy for implementing our device in the future. Another important point he reiterated was, that instead of targeting the affected water bodies, it would be more efficient if we could tackle the problem right at the source itself. He explained to us how that model would not only bring down cost, but help avoid the unpredictability of the composition of water being cleansed.

From our discussions and meetings with Prof. Purnendu Bose and Prof. Rajiv Sinha we decided to make two products based on the ability of SDSase to remove SDS detergent from wastewater. One of the products is aimed to be implemented at a household level, while the other is product is aimed at direct installation at River banks and places where massive discharge of detergents takes place into the rivers( places in india referred to as ‘Dhobi ghat’). It would be costly and inefficient to create live models to test our product, furthermore predictive modelling and CAD softwares enable product visualisation and implementation without the needing to go with costly manufacturing of the product. Hence for pre-prototyping we created AutoCAD based models of our products:

1. Household level SDS degrading bioreactor

This device is meant to be implemented at a household level. The basic idea is to take the detergent rich water directly from the washing machine, collect it and treat it to send it back to the washing machine.

Fig .1(above) The household SWASH water treatment device, the multi-functioning lid and the incubator are mount atop the separation column. The collection(grey) and dilution(blue) chamber are below the separation column. Pipes from the Collection and Dilution chambers then go into the reaction chamber(cube in shape).

The device has a total of 5 sub components -

-Bacterial Incubation Chamber (BIC)

The BIC sustains the e. coli culture and allows it to produce SDSase in the culture itself. Thus there is no need to add SDSase protein separately into the machine and the machine is thus able to generate its own SDSase. Its design is based on standard laboratory incubators and consists of an anodized aluminium box with thermally insulated wall and an inner borosilicate lining to provide inertness to the culture walls. To maintain conditions for the viability of the bacteria, its lid is equipped with an induction based heating coil and aerator to maintain the temperature at an optimum of 37 deg celsius and provide optimum aeration and oxygenation for the culture.

Fig .2 a,b,c(above) a) The lid assembly with the incubator, b) the aerator attached to the lid, shown by the cube with a circular hole in the lid, c) The induction based heater attached to the lid.

-SDSase Purification Column

Along with the SDSase in the solution, there are other substances in the culture solution which are necessary for growth of bacterial cells but not required for cleaning the water, and instead serve to pollute the water. Hence our household device should only transport SDSase to the washing machine discharge and not or the bacterial cells. To separate these from SDSase solution we require a selective factor. Particle size of components of LB are way smaller compared to SDSase and differentially preferred adsorption of these small components of LB compared to SDSase serve to remove LB from the solution. A cheap method to accomplish this is by slowly running the culture solution through a pipe whose walls are lined with hydrogel (Kim, J.J. & Park, K. Bioseparation (1998) 7: 177. https://doi.org/10.1023/A:1008050124949) which serves to provide differential adsorption to the LB components. This way we can achieve separation of SDSase from LB components.

-Collection and Dilution Chambers

These are the two chambers located below the incubator. The grey chamber is the collection chamber where the SDSase is collected after passing through the separation column. The Blue chamber is the dilution chamber which stores distilled water to help dilute the concentration of SDS from the washing machine to maintain ambient concentration of SDS for the functioning of SDSase. This ambient functioning is set at approx 0.21% w/v (kg/l) of SDS conc, with about only 4% SDSase w/v (kg/l) and this achieves about 75% SDS degradation (Ambily, P. S and M. S. Jisha, School of Biosciences, Mahatma Gandhi University, Kottayam). Taking into account an average concentration of 0.03% (kg/l) of detergent in a single wash of washing machine (Handbook of Detergents Part E: Applications, Uri Zoller), SDSase concentration is diluted to 0.57% and subsequently sent to the reaction chamber.

Fig .3(above) Cross sectional images of the separation column(top grey cylinder), collection chamber(below grey cylinder) and dilution chamber(blue cylinder)

-Inlet and Filter

This inlet collects water from the washing machine and loads it into the Bioreactor. It is composition is a polycarbonate plastic shell and wire mesh as a filter to filter out any small residual cloth strands from the washing machine discharge.

Fig .4 a,b(above) a) Inlet takes discharge directly from the washing machine and transfers it to the Bioreactor, b) Mesh based filter attached inside the Inlet

-Bioreactor

The Bioreactor serves as the main unit where Washing machine discharge and purified SDSase are collected at ambient concentrations of 0.03%(w/v SDS) and 0.57%(w/v SDSase) and allowed to react. It’s walls have an outer aluminum layer and an inner Borosilicate lining by providing inert walls to facilitate the reactions. An average top-loading washing machine takes in and discharges 40 gallons of water(0.151 metre cubed), hence to hold it the dimensions of the bioreactor are 0.6X0.6X0.6 metre cubed.

2. Direct River implementation based Reactor

This device is an onsite installation device implemented at the river banks and partially submerged underwater. It’s inlet and outlet are inside the river while the bacterial incubation chamber is above the river body. Due to its the fact that it should work for long time periods inside a river, minimal moving parts are present, such as the rotor to allow the water inside and the rotor that allows the water to leave the chamber. Further there is no precaution taken to clear out the SDSase or LB from the chamber as the water is released to the natural river biome which can digest and degrade the biodegradable substances such as LB and SDSase on account of high protease and bacterial content in river water.

Fig .5 Front and Back Views of the On-site River Reactor. Above is the Incubaton chamber with an aeration enabled lid. Only one of the 4 reaction chambers(which are symmetrically placed quarter cylinders) are shown for clarity, the inlet and outlet gates of the chamber are controlled by rotors. The incubator is linked directly to the Reaction chamber.

It has 4 simple parts, the simplicity prevents wear and tear and prolongs its functioning life in the river minimising need for changing mechanical parts:

Incubator

It’s design is very similar to the incubator for the household device and it too serves to incubate e. coli and produce SDSase without requirement of external addition of SDS. Unlike the house based reactor, the SDSase is not filtered from the incubator before being sent to the main reaction chamber.

-River Inlet and filter

We employ a rotor based mechanism for the the control of the inlet gates to allow the water to enter the reaction chamber. A wire mesh is employed to filter out any impurities from the river.

-Reaction Chamber

The reaction chamber directly gets water from the river and also gets the SDS culture from the incubation chamber without any filtering.

-Outlet and Discharge into the river

After SDS is degraded by the alkyl sulhaptase(SDSase) in the reaction chamber, the treated water along with LB, bacterial cells and SDSase are discharged into the river biome. The high presence of protease and other bacteria in the river water can hence degrade these extra components.