Prof. Ligy Philip (Principal Inventor) and Mohammed Iqbal Thayyil (Research Scholar)

Untreated discharge of municipal wastewater is a significant contributor to the pollution of water bodies, leading to water scarcity. Due to the operational and economic limitations associated with centralized sewage collection and treatment, there exists a need for a decentralized approach to municipal wastewater management. In this context, removing the pollutants from the water as it flows along the channel/drain is an attractive option to arrest the deterioration of receiving water bodies. In-stream treatment using ecosystem-based engineered systems is of particular interest as it does not involve major structural modifications or energy-intensive operations. Using locally available natural materials and resource recovery from such a system can enhance the overall sustainability of the treatment process while ensuring water security. Henceforth, a sequential treatment involving anoxic biofilm, aerobic biofilm and hydroponic system was evaluated on a lab scale after optimization of each of these individually. For the field scale application, the overall treatment process can be divided into three parts: pre-treatment, attached growth microalgae-bacteria consortia (MABC) treatment and post-treatment. In the pre-treatment stage, large floating matter and settleable solids are removed by screening and sedimentation. A fraction of soluble organic matter is removed by the anoxic attached growth biofilm treatment step, in which modular units of porous bunds of autoclaved aerated concrete (AAC) encased within stainless steel mesh are introduced into the flowing drain. This is followed by the removal of nutrients and the remaining fraction of organic matter by harnessing the symbiotic interaction between photosynthetic microalgae and bacteria consortia (MABC) attached to a coir fibre mesh. The last stage of treatment involves phytoremediation using Canna indica plants in a floating treatment wetland configuration.

The sequential application of these techniques could bring about a COD removal of 85% and ammonia-N removal of 96.8%. The use of microalgae-bacteria consortia biofilm could offset the need for external aeration during the aerobic treatment stage. Hence, a practically applicable in-stream treatment system was developed, with a potential field-scale application for the remediation of contaminated drains.

Prof. Ligy Philip, Vaishali Choudhary, Dr. Kowsalya Vellingri

Eutrophication of aqueous system refers to the presence of excessive richness of nutrients such as nitrates and phosphates in the aqueous system, thereby causing destruction or extinction of aqueous system. Monitoring of water bodies can be accomplished by collecting discrete measurements of water quality parameters in the field or laboratories. With the technological advancements, "real-time" monitoring of water quality is also being investigated as a possible solution. However, the cost of installation and maintenance is one of the major issues. Additionally, for the Indian scenario, enveloping water bodies with a real-time monitoring system is problematic due to large watershed areas and limited wastewater treatment units.

The aforementioned are common issues in many developing and underdeveloped countries. Thus, low-cost water quality sensors that monitor water quality parameters specific to eutrophication are needed. The present invention is portable and easy to use paper sensor, facilitates easy and ready monitoring of the eutrophication of aqueous system by onsite/ online monitoring of target ions (phosphate) in water bodies, thereby providing an easy solution to take suitable steps to prevent the loss of aqueous system. The high selectivity of the developed paper sensor is attributed to the proper selection of the substrate, probe and binder. The papers sensor is low-cost and selective. The developed sensor is easy to use, adding a drop of liquid reagent (dyes) or dipping the strip in the water sample. As suggested by the regulatory, the threshold limit or permissible limit of pollutants can be detected via the naked eye. Hence, before the complete deterioration of water bodies, a quality check and possible treatment plan can be formulated. The sensor shows selective performance in the presence of other co-existing ions. No toxic by-products are generated during the course of the reaction. The fabricated sensor should be highly stable under environmental conditions and easily stored. The scaling up of the production of the sensor should be easy. Therefore, readily accessible and affordable chemicals and immobilizing substrates should be utilized. The sensor can be used for on-site analysis, quantification, and conventional spot test practical experiments.

Prof. Ligy Philip, Vaishali Choudhary

Municipal wastewater contains a high load of nutrients like ammonia, nitrate, and phosphate, which if left untreated, can cause eutrophication and a decline in water quality. On the other side, the natural reserves of phosphate are exhausting rapidly. Thus, wastewater can be considered as an untapped resource for recovering nutrients like phosphate. Traditional techniques like chemical and biological dephosphorization are most commonly used to remove phosphate from wastewater. The precipitation of phosphate as struvite or enhanced biological phosphorus removal in the activated sludge process allows the capture of high concentrations of phosphate (> 5 mg/L). However, the efficacy of the process is affected at a lower concentration range. Accordingly, electrochemical methods like electrosorption enable easy removal and recovery at lower phosphate concentrations in wastewater.

The capacitive deionization or electrosorption (ES) is considered as a competitive alternative to state-of-the-art technologies for selective scavenging of ions due to its low energy requirement < 0.5 kWh/m3), the process works at electrode potential below water oxidation potential (1.23 V), high recovery, zero requirement of chemicals, and easy operation. However, the major issue in the effective removal of anions like phosphate using ES is the high hydration enthalpy of phosphate ions, poor selectivity, and limited charge storage capacity of traditional activated carbon electrode. As a result, developing a system that can selectively remove phosphate is essential. In this context, the current invention discloses electrode materials like Zn-Co layered double hydroxide synthesized via co-precipitation and urea hydrolysis and intercalated with different anions such as Chloride, Nitrate, Carbonate, which when employed as active electrode removes and recovers phosphate from aqueous phase under an applied potential of 0.8 V to -1.0 V, respectively. The chemical free phosphate recovery of 98.6 can be achieved using the system.

Prof. Ligy Philip, Prof. Sarathi R, Dr. Raj Kamal Singh, & Sumit Kumar

1. Patent No: WO/2019/092747 Dt:16-5-2019 (International)
2. Patent No: 349146 Dt:13-10-2020 (National)

With the rapidly growing population, the consumption of water is doubling every 20 years and it is estimated that 3 billion people would be living below the water stress threshold by 2025. Along with the high demand for consumption, a large amount of water is wasted in agriculture, industries, and urban areas. Untreated sewage or untreated/partially treated industrial wastewater discharge in surface water leads to determinant health problems. The presence of emerging contaminants (ECs) such as pharmaceutical compounds and pesticides in surface water bodies (rivers, lakes, streams, etc.) has increasingly been recognized as a threat to the aquatic and terrestrial ecosystem. Along with its contamination, pathogenic microorganisms in drinking water sources also show determinant adverse health effects. As estimated by the world health organization (WHO), 84200 diarrheal deaths are related directly to pathogenic contaminant water. Existing treatment of ECs has bioremediation, Fenton oxidation process, ozone technology, photo-catalytic process, and electrochemical process which showed selective degradation of pollutants in mixed ECs-contaminated water. Moreover, the major concern about the degradation of ECs by the aforementioned AOPs leads to products that might be more toxic than the parent compound. Similarly, for removing pathogens from drinking water sources, chlorination, UV treatment, and ozone treatment are the most used technologies. However, the formation of carcinogenic by-products such as trihalomethanes or halo acetic acid in chlorination is the main disadvantage. Therefore, the water system must remove ECs as well as pathogens from drinking water sources to negate their adverse health effect.

The present invention is continuous flow plasma technology for the removal of pestic(d) Discharge of treated water through the reactor.ides(d) Discharge of treated water through the reactor., PACs, and pathogens from contaminated water for drinking purposes. In this technology, untreated water flows as a thin film to the plasma region and undergoes oxidation by different reactive species, then treated water is discharged through the reactor. The treated water meets the drinking water standards and the method can serve the purpose of water disinfection and ECs removal as a single unit.

The present invention provided a water treatment process that comprises different steps:

1. Pesticides, PACs, and bacterially contaminated water is treated in a pulsed power reactor to produce drinking water, which meets the drinking water standards.
2. Flowing of untreated water as a thin film so that the maximum surface area of untreated water gets exposed to plasma.
3. Untreated water enters into the plasma region and undergoes oxidation by different reactive species.
4. Discharge of treated water through the reactor.

Table 1 – Different water quality parameters monitored in raw and treated water (after 24 min treatment) samples

Through this work package, we aim to develop a holistic design and planning framework involving low impact development techniques for sustainable water management. Low impact development techniques (LIDs) intend to reduce the generation of storm water runoff from its source sites as well as to provide storage and infiltration for storm water through sustainable drainage options. Although LIDs are gaining popularity around the globe, there exists some challenges which need to be addressed through research such as: identification of potential sites for effective implementation of LIDs; design and sizing of LIDs using process-based models at local scale; and identification of optimal combination of LIDs for regional scale planning and implementation. The technologies that are being developed through this study involves: (i)advancements to existing softwares such as SWAT for regional level planning of LIDs (ii) coupling of existing softwares such as SWMM and HYDRUS 1D for LID performance assessment, (iii) setting of hydrological and hydrogeological observatories for data collection and (iv) site suitability analysis for LIDs using hydrological modelling and analytical hierarchy process.

Through the hydrological and hydrogeological observatory that has been set up in the IIT madras campus, data collection on channel flow, rainfall, groundwater levels and soil hydraulic properties was made possible. This has enabled the development of SWMM model for the IITM catchment and a coupled SWMM-HYDRUS 1D model (through pySWMM and pyHYDRUS) for assessing the performance of different types of LID techniques under various meteorological conditions. For regional level planning of LIDs at larger spatial scales, LID modules based on Multi-Layer Green-Ampt infiltration model have been developed in the study and were verified using process intensive HYDRUS 1D model which is based on Richards’ equation. The sensitivity of the modules to varying native soil conditions was also studied by testing the modules with various soil samples sampled over the soil textural traingle. These process based LID modules will be then incorporated into the sub-routines of SWAT model which will facilitate hydrological modelling of large catchments along with LID modules. Along with designing and modelling LIDs, placing them at suitable locations is necessary to make the implementation effective. Through site suitability analysis, we tend to develop site suitability maps for Chennai basin, which shall aid the policy makers and planners to place LIDs at effective locations. A hydrological model for the basin has been set up in SWAT for this purpose, from which the rainfall and runoff characteristics will be obtained for developing the site suitability maps for LIDs using analytic hierarchy process. Using the site suitability analysis, the study will attempt to further regional level planning of LIDs using simulation-optimization techniques in the improved SWAT model. Optimization will allow the placement of optimal combination of LIDs at suitable sites so that storm water runoff regulation and ground water recharge augmentations are met. The optimization framework is currently in the stage of development.

Introduction :

High level of fluoride (F-) contamination in groundwater is a serious issue that affects more than 200 million people in 25 different nations. To maintain safety, it is crucial to accurately quantify as well as identify aqueous F-. Here we have developed a cheap, handheld, portable mobile device for colorimetric detection and rapid estimation of F- in water by the application of the synthesized core-shell nanoparticles (near-cubic ceria@zirconia nanocages) and a chemoresponsive dye (xylenol orange).

Key features:

• Principle of operation-Online colorimetric sensing
• Detection range-0-12 ppm with in-built auto-dilutor
• Error - ~10 %
• Calibration-Automatic based on user selection
• Cost per measurement - ~ 2 INR
• Measurement frequency-User defined.Min interval between two measurements is 10 min
• Interface-Any IoT or Bluetooth platform
• Other low-cost option-Pocket device interfaced with the smartphone (Manual operation)

Figure: (A) Graphical representation of the extended sensor device cum sample holder. (B) Photograph of the sensor extension cum sample holder. (C) Photograph of the F- sensor integrated with a smartphone.

Reference:

Mukherjee, S.; Shah, M.; Chaudhari, K.; Jana, A.; Sudhakar, C.; Srikrishnarka, P.; Islam, MR.; Philip, L.; Pradeep, T. Smartphone-based Fluoride-specific Sensor for Rapid and Affordable Colorimetric Detection and Precise Quantification at Sub-ppm Levels for Field Applications. ACS Omega. 2020, 5, 25253-25263.

Water scarcity is increasing day by day due to increasing population per unit area in urban areas. Effective treatment of wastewater and reuse of water is important in tackling the problems of water scarcity. Reuse of water reduces the load on valuable ground water reserves, and also reduces the drainage burden and environmental degradation. There have been many reports on the lack of hygiene and sanitation facilities in schools. Though the toilet infrastructure is available in many schools, in many instances it is in an unusable condition due to lack of water supply. Wastewater generating in schools is often contains low (chemical oxygen demand (COD) and very high ammonia, mainly due to the urine released depending on the usage pattern. This is a bottleneck, for the treatment of the specific wastewater by conventional technologies such as septic tanks. Therefore, there is a need to develop system or battery of systems, which can treat the wastewater to a desired efficiency in a sustainable and cost-effective way.

In this work, we developed a method and a system for treatment of wastewater powered by solar energy comprising mechanical filtration in screen chamber, solid-liquid separation in a modified septic tank (MST) with inclined plates at the inlet, removal of organic matter in an aerobic attached growth system to obtain biologically filtered clarified water, filtration by a rapid sand filter for non-organic contaminant removal and finally ensuring of the quality of the treated water by monitoring system before storing it for non-potable use. Solar powered system for treatment of wastewater provides opportunity to operate decentralized wastewater treatment system in a sustainable manner. The system for treatment of wastewater can be a standalone unit or a unit that is integrated into an existing toilet system. The developed system is useful for saving fresh water and also for saving the energy required to transport the wastewater and its treatment cost. A system has been developed, installed in a school and it is in operation. We are working with potential partners to copy such system elsewhere.

We have developed new water quality and quantity monitoring sensors and associated systems that are less expensive and reliable, by the virtue of the method, materials used and processes employed.

The first work was focused on the development of the basic principle of a noncontact method of measurement of the conductivity of liquids and the associated design rules to have a minimal error in the measurement. In this method, the current is sent through the liquid whose conductivity is to be measured by conduction, and the voltage across the liquid column is measured using capacitively coupled electrodes, and the conductivity is computed therefrom. The capacitively coupled method is new. The sensor requires no coils and high permeability material which are unavoidable in the case of inductive probes. This work was done with the support of National Institute of Ocean Technology while Sutram supported further practical evaluations. Currently an industry partner is making multiple units of the same for field tests.

In the second part of the research, we focused on developing a new water-level-sensing mechanism that is based on planar coils fabricated on a low-cost printed circuit board (PCB). In addition to level, this sensor detects any relative increase in conductivity compared to that of clean water, which is an indicator of the quality of water. The sensing mechanism utilizes the eddy current induced in the water column, the corresponding change in the coil inductance, and the change in the turn-to-turn capacitance of the coil in the presence of water. Since both water quantity and quality measurements are fundamental in realizing efficient water and wastewater management, obtaining these two parameters from the same sensor is very beneficial. The sensor is modular and hence scalable for large length depending on the depth of the tank.

Details of the patents granted and filed are given below.

1. Ligy P., Boby George, Krithika D., Gaurav L., and Subham K. S., "A Method and System for Treatment of Wastewater Powered by Solar Energy",(201841039386, 17/10/2018), (Granted, Indian patent number 394888, 07-May.-2022)
2. Tejaswini K. K., Bijoy K. P., Boby George, Jagadeesh Kumar V., Atmanand M. A., R. Srinivasan and Tata Sudhakar, "Device and Methods for Conductivity Measurement of Fluids", Indian patent number 410165, 28-Oct.-2022, Status: Granted.
3. Gaurav L., Subham K. S., and Boby George, Subhas C. Mukhopadhyay and Ligy Philip, "A Planar Coil-Based Water Level and Quality Monitoring System", (201941021491, 24-July-2019).

A novel patented process of zero sludge discharge and aerobic granulation system was developed for simultaneous removal of C, N, and P in a process controlled lab-scale sequencing batch airlift reactor. Synthetic wastewater was used to develop the process know-how. Aerobic granules of size 1.5 to 3 mm were developed at operational DO of 1 to 2 mg/L involving heterotrophic nitrification and aerobic denitrification. Stable granular biomass could be developed by optimizing DO and feed cycle intervals in SBR. The developed process could deliver simultaneous removals of COD (90.1%), Total Nitrogen (90.6%) and PO₄ ³--P (83.2%). Zero sludge discharge was obtained by a long starvation period in a cycle using feed-famine mode. Alternatively, the same process was developed in a conical geometry SBR with simple operation without any process control. Stable granules measuring around 0.9±0.3 mm with good settling properties could give removals of COD (90%), NH4+-N (91%), total nitrogen (87%), and PO₄ ³--P (83%). The process-know is helpful for designing appropriate compact reactor system for low volume wastewater treatment in University campuses, small townships, and in apartment/commercial complexes. In order to prove its efficacy and efficiency in real life situations, a pilot scale study is required as a next step before full-scale application in wastewater treatment plants.

The process know-how of the developed process is available in the following patent and publications.

(1) Indian Patent Application No: 202041032265, Zero sludge and aerobic granulation system for simultaneous removal of C, N, and P in sequencing batch airlift reactor.

(2) Development of aerobic granulation system for simultaneous removal of C, N, and P in sequencing batch airlift reactor, Journal of Environmental Chemical Engineering, Vol.9 (5), 1-13, 106100, https://doi.org/10.1016/j.jece.2021.106100.

(3) Development and long term operation of aerobic granular system for simultaneous removal of COD, nitrogen, and phosphorous in a conical SBR, Environmental Engineering research, 28(3): 220015. DOI:10.4491/eer.2022.015.

Nikita Shraogi ^{1, 2, 3} , Rahul Verma ^{1, 2, 3} , Joel Saji1, 2, Amrita Singh ^{1, 2, 3} , Sneha Verma ^{1, 2, 3} , Durgesh P Mourya ^{1, 2, 3} , Alok K Pandey ^{1, 2, 3} , Satyakam Patnaik ^{1, 2, 3 *}

¹System Toxicology and Health Risk Assessment Group, ²CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, Lucknow-226001, Uttar Pradesh, India.³Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India. ^*Corresponding author.

With the advancement of technology, the use of new and improved materials starting from macro to micro and nano-range, for applications in varied fields has increased exponentially. Although, the interest of the scientific diaspora has been inclined towards nanomaterials, owing to the unique properties they possess, yet, the use of these innovative materials has given rise to concern regarding their potential toxicity on living beings as well on the environment. This chapter elaborates on how emerging nanomaterials behave in relation to dynamic microenvironments at the nano-bio-eco interface level and how this affects their toxicity, fate, and exposure potential. Besides, a brief account of the exposure pathways and different models used for toxicity evaluation is also discussed, vis-à-vis the ongoing research work on the toxicity, the role of contributing factors, and the probable alternatives developed to attenuate related hazards, challenges, and future outlook.

Contents:

• Introduction
• Aquatic environment exposure of emerging nanomaterials in aquatic systems
• Emerging materials: Nanomaterials, Polymers, Graphene-based materials, Metal-Organic-Framework (MOFs), Covalent Organic Frameworks (COFs), Other materials
• Fate and toxic behavior of nanomaterials with respect to their properties or Potential Toxicity of Emerging Materials
• Possible exposed biological systems
• Exposure Pathways and common mechanisms of nanoecotoxicity in the aquatic environment
• Toxic effects on planktons
• Toxic effects on microbes
• Crustaceans
• Fishes
• Amphibians
• Methods of Toxicity Evaluation
• In-vitro methods
• In-vivo models: Plant models, Aquatic models: algae, Daphnia, Zebrafish, Soil organisms: Bacteria, earthworm, Terrestrial organisms: Honeybee, Ladybugs and Rodents.
• Exposure to humans
• In vitro: Metabolic activity, membrane integrity, cell proliferation, apoptosis detection
• In vivo: Blood contact properties, Immune System Response, Toxicokinetics, Biodistribution
• Factors contributing towards toxicity enhancement
• Greener Alternatives to lessen toxicity
• Challenges and Future Outlook
• Conclusion

A portable and resource-efficient film-forming silver nanoparticles-based nanocomposite (AgNC) has been synthesised for the disinfection of water. The composite film is packed in a nylon sachet, and a simple ‘dip and sip’ point-of-use disinfection system is developed for personal and household use. Unlike unprotected silver nanoparticles, the present system enables the controlled and sustained release of silver ions into the water. The AgNC is hydraulically stable and has excellent mechanical strength. One gram of AgNC can treat around 100 to 200 L of water and at less than 5 paise per litre. The nanocomposite-treated water did not produce any cytotoxic effect against human keratinocyte cell lines (HaCaT), and it is safe for consumption.

A point-of-use household disinfection system has been developed, coating AgNC onto functionalized sand particles. The unit consists of two cartridges connected in a series, as shown in the figure below. The first cartridge is made of AgNC-coated sand that enables the controlled release of silver ions into the water. The second cartridge consists of activated carbon, which removes excess silver, endotoxins, and other organic impurities in water. The laboratory study shows that the unit can provide microbial-free for a family of 5 persons (20 L/day) for nearly six months with occasional regeneration. The concentration of silver is well below the permissible limit, and the water is safe for drinking.

In this work, a novel strategy has been developed to recycle the spent AgNC into a microcracks sealant through a soft-chemical route. The sealant developed is the first of its kind and has the excellent ability to plug structural and non-structural cracks in concrete (cracks width <0.3 mm). The sealant can penetrate deep inside the cracks and solidify in a concrete environment (alkaline environment). The sealant is stable in an alkaline environment and can flow deep inside minute cracks.

Abhijit Patra and coworkers, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, Madhya Pradesh, India Sulfonated solvent-knitted HPOPs have been demonstrated for rapid removal of broad-spectrum polar organic micropollutants, including plastic components, pharmaceutical drugs, ionic dyes, herbicides, pesticides, and phenolic and amine compounds from water with remarkable separation efficiency (within 30 s under environmental concentrations) and high recyclability. The work (ACS Appl. Mater. Interfaces 2022, 14, 7369) has received wide media coverage and press release in the national media, highlighted in The Better India, Telegraph Inida,Vigyan Prasar,India Today, NDTV, Hindustan Times,The Hindu  among many others. The work has also been featured in Sansad TV in Science Monitor  and  episodes.

The presence of organic and inorganic species in drinking water could not be avoidable, and it would have originated either naturally or through human activities. While the presence of metal ions, anions, etc., in water are essential nutrients for the human body, excess of it could be lethal. The conventional qualitative and quantitative detection method involves sophisticated instruments and skilled manpower, which may hinder the on-sight analysis in remote areas. Thus, deploying molecular or nanomaterials-based sensors, which could accurately identify the specific target species at low concentration levels, offers the cost-effective, real-time testing of water samples without the requirement of skilled manpower. We developed a simple test protocol using colorimetric, fluorescence, and electrochemical methods.

• An aqueous solution of the probe turns pink to orange when the water contaminated with mercury is added. At the same time, the presence of other metal ions does not affect or interfere with the reaction between the mercury and the probe, thus highly selective towards mercury alone. The detection limit is ~9 ppt (parts per trillion), a much lower value than the permissible limit in drinking water prescribed by regulatory bodies like the US Environmental Protection Agency (EPA) and the Bureau of Indian Standards (BIS).
• The second approach employs the thymine and carbodiimide functionalized graphene-modified electrode, which could selectively sense Hg(II) and Cr(VI) with a different signals without interfering with each other. It could work even at higher TDS levels. A handheld, low-cost analysis device was constructed, which could be used with the conventional three-electrode electrochemical cell or a screen-printed carbon electrode coated with functionalized graphene. The instrument is portable and could detect both metal ions even at 100ppb level.

A novel dynamic optimization process of a multi-reservoir system was developed among the Chembarambakkam reservoir of Chennai, and nearby two quarries (i.e., Sikkarayapuram and Erumaiyur) under the SUTRAM project. The proposed method can help with flood mitigation, considerably reduce evaporation loss from the reservoir and improve Chennai city's water supply. The optimization helps in flood mitigation by 0.5 TMC that occurred in 2015 to 0.3 TMC, and evaporation loss reduction by 17% in a day, simultaneously improving the water supply. Generally, the optimization of reservoirs considers and focuses on the major requirements like water supply, irrigation, power generation, etc., and evaporation and infiltration are considered as just losses. Here, our proposed optimization approach in daily time step prioritizes and quantified the water that could be harvested through evaporation loss reduction followed by optimization and its reflection on improving the water supply of Chennai city. The approach was proposed to reverse the situation that Chennai city faced in 2015 (floods) and 2019 (day zero, water scarcity).

1. Development of portable Microbial Fuel Cell (MFC) for simultaneous energy harvesting and wastewater treatment

   An array of interlinked MFC’s has been developed which can reduce the oxygen depleting potential of a range of wastewater with simultaneous generation of captive electricity in utilizing to improve the system performances.

2. Integrated MFC-MEC systems for biohydrogen productions

   A Microbial electrolysis cell (MEC) system has been developed, propelled by the energy generation in the MFC system, for increasing biohydrogen production and water purifications, using various organo-rich wastewater