Dr Hitesh Sukhwal, Deputy General Manager (Environment), Udaipur Cement Works, discusses the importance of efficient water management in a cement plant, to make production more sustainable and water positive.
Tell us about the role of water in the cement manufacturing process.
Cement manufacturing is a dry process. Previously, the cement manufacturing process was based on a wet process. At present, about 99 per cent of installed cement industries in India use the dry process of manufacturing. Cement production requires water for cooling of heavy machineries, vent gases, in operation of captive thermal power plant/waste heat recovery boiler, etc. Hence, water conservation and management are important environmental aspects for all cement companies.
Does the process of cement manufacturing impact water positivity of the organisation?
As stated earlier, there are two processes of manufacturing of cement i.e. dry and wet. Dry manufacturing is now the dominant process in India as well as across the globe. When we talk about consumption of water in the dry process, there is no direct mixing/use of water in the process itself to produce cement. Water is only used for cooling purposes, generation of power and mitigation of secondary pollutants at some places in the process layout.
On the contrary, in the wet process of manufacturing, water mixes with raw material to make slurry and feeds into the wet process kiln for drying and calcination to form clinker. The wet process requires a large amount of water, which is a significant environmental concern. In addition to that, the wet process is much more expensive than the dry process, due to a large amount of energy required to evaporate the excess water in the slurry.
Process cooling is a major component of water consumption in the cement industry. During the cement manufacturing process, a large amount of heat is generated by the pyro-processing. Water is used to cool down at various stages, likely the exhaust gases from the kiln, pollution control equipment, compressor, etc. during the process cooling, a large amount of water lost through evaporation and blowdown. The cooling water is usually recycled within the plant and replenished with water lost due to evaporation.
Earlier, in most of the cement plant, a major cooling device was a Gas Conditioning Tower (GCT). The tower was used for reducing the flue gas temperature from pre-heater before entering a dust separation system like ESP/Bag filter. Now, the cement industry replaced such types of GCT with a robust pollution control system and waste heat recovery boiler for power generation.
Now, cement industries are only dealing with solids and gases. In other words, water utilisation is only counted during the cement product life cycle but not in the cement manufacturing processes. Dry manufacturing process, the 3Rs principle, water positivity, etc. will sustain the cement business.
Tell us about the ways in which water is conserved in a cement plant.
Efficient water usage during the cement manufacturing process is a key performance indicator for the cement industry. In India, major cement industry clusters are in dry and arid regions of water scarcity, such as Rajasthan and Andhra Pradesh. Green-based solutions like rainwater harvesting and artificial recharge structures are two key components for water conservation within and beyond the fence.
The change in cement manufacturing technology from wet to dry was a paradigm shift for cement production. The story of water conservation started from the dry manufacturing process in cement production. Although there are no direct uses of water in the dry process, it is still one of the important resources for cement production. If the cement plant is in a dry and arid region, then water consumption can become a significant issue.
Cement industry has taken various steps of water conservation and management as stipulated below:
Transition of manufacturing process from wet to dry – paradigm shift.
Industry is framing up water conservation and management policy and abiding with.
Encouraging water footprint assessment as per ISO 14046:2014 and water audit from competent authority for effective implementation of conservation and management aspects.
Industry is abiding with 3Rs principle i.e. Reduce, Reuse and Recycle for water conservation
and management.
Adopted zero liquid discharge (ZLD) system. This is a closed loop wastewater management system with a high recycling rate and no discharge of industrial wastewater into the environment.
Installed Air Cooled Condenser (ACC) for its captive thermal power plant instead of water-cooled condenser.
Process optimisation for lesser water consumption.
Adopting air cooling-based compressors instead of water cooling.
Overhead water pipeline to address leakage promptly, instead of underground for all kinds of operational machines.
Increase share of renewable energy sources which require less/zero water requirement for power generation, such as solar energy (water required only for panel cleaning) and wind energy (zero water requirements).
Installation of waste heat recovery boiler-based power plant along with ACC for cooling purposes.
Strengthened monitoring and measurement for 24×7 hrs. of water consumption through Industry Internet of Things (IIoT).
Installed online monitoring systems to check 24X7 wastewater quality for taking prompt action to maintain the quality of water.
Automatic water (sensor based) sprinkler for haul roads in mine, sensor based fogging system for dust suppression over mine’s crusher hopper.
Automatic drip irrigation for horticulture use.
Paved road and parking area for minimal use of water to prevent fugitive dust emissions.
Deployment of road vacuum sweeping machine for housekeeping.
Sensor-based water tap for office, canteen, guest house etc.
Installed efficient Sewage Treatment Plant (STP) and effluent treatment plant for automobile workshop and captive power plant.
Digitalised 24X7 monitoring and level checking.
Constructed artificial recharge structures for augmentation of ground water table. Harvesting rainwater through a mine pit and artificial pond within and beyond the fence.
Encourage community participation for water conservation and management through CSR activity such as watersheds, village ponds, bunds, check dams, wells, drip irrigation, etc.
Educating and conducting awareness programmes for community, schools, employees, suppliers and vendors on water conservation aspects.
Afforestation and green belt development with maintaining local biodiversity.
Moreover, the regulatory authorities are also creating standards (for quality and consumption) to make industry water efficient. For instance, recently the Ministry of Environment and Forests and Climate Change (MoEFCC) notified a standard on water consumption for thermal power plant i.e. new plants shall have to meet specific water consumption up to maximum 2.5 Cum per MWh and achieve zero wastewater discharge, installed after 01st January 2017. The Central Ground Water Authority (Ministry of Jal Shakti) also notified standards and guidelines on groundwater abstraction and imposed abstraction/consumption fees in different categories.
Elaborate the steps taken by your organisation to reduce its water footprint.
Our commitment is to reduce freshwater consumption and increase utilisation of wastewater after necessary treatment. We are emphasising upon harvesting rainwater in mine pits and artificial ground water recharge structures. Process optimisation is a key performance indicator for our cement production on every environmental aspect like energy, raw material and water uses.
We have implemented all the above points to reduce our water footprint. We have developed an in-house IoT based monitoring system in all our units. Recently, we developed a mini dense forest in a 4000 sq metres area to maintain local biodiversity, prevent soil erosion and for augmentation of ground water table, which is a nature-based solution.
Has your organisation achieved milestones with respect to water positivity?
Around 70 per cent of the Earth’s surface is covered with water, but only around 3 per cent is fresh water and barely 1 per cent is usable for humanity since most of the freshwater is frozen in glaciers and in polar ice caps. Water is a scarce resource and an essential component for every living creature on the earth. As availability of freshwater is scarce, cement industries are committed to reduce their water consumption and enhance water management.
Udaipur Cement Works Limited (UCWL) has done considerable work in water conservation and becomes 3.6 times water positive (FY 2022-23). We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24X7. All digital metres and level recorders are being monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. The Effluent Treatment Plant (ETP) is installed for the mine’s workshop. Treated water is being reused in washing activity and the unit is maintaining ZLD.
UCWL installed a unique floating solar power plant in mine, which reflects the company’s innovative approach towards reducing carbon emissions and water evaporation. This floating solar power plant will help the company to save nearly 8000 cum per annum water due to decrease in evaporation loss. Going beyond the general industry practice, the company has also inventoried its carbon and water footprint as per ISO 14064–1 and ISO 14046.
How do you measure water positivity and what are the ideal benchmarks?
Water positivity means creating more freshwater than what is being used in the manufacturing process and other business activities. However, new water cannot be created, so the focus of water positivity is on the efficient use of water, and to recharge and harvest more rainwater from the ground and/or from the Earth’s surface. A water positive cement plant draws minimal freshwater from ground/surface source, consumes 100 per cent self-generated wastewater for its processes and puts more freshwater back into nature (ground/harvest). Reducing dependency on freshwater is also one of the best ways to become water positive.
UCWL is abiding by the guidelines of CGWA (Ministry of Jal Shakti) to implement and estimate ground water recharge potential and harvest rainwater. To become a water positive company, we are putting our all efforts on monitoring, measurement and mapping of water withdrawal, consumption with the help of artificial intelligence (AI). It is a long journey. At present we are 3.6 times water positive, and we are determined to increase the potential of it. The ideal benchmark is continual improvement in conservation of this precious natural resource. We must improve at all levels like process optimisation, green / clean energy use, monitoring, measurement, awareness and individual responsibility to save water in all aspects.
How do communities surrounding your plant contribute towards your water footprint?
UCWL is continuously doing efforts on minimal use of fresh water from ground. Unit has installed artificial ground water recharge structures, dug ponds, watersheds for augmentation of groundwater tables. We are educating our surrounding stakeholders (especially schools) and raising awareness about the importance of water sanitation, hygiene and conservation. Udaipur city is known for its lakes worldwide. We have conducted lake cleaning drives with our stakeholders.
Harvesting of rainwater in a mine pit and implementation of artificial ground water recharge structures is impacting groundwater tables and improving the quality of water of surroundings. We have installed an online piezometer and digital water monitoring for 24X7 checking and monitoring.
Tell us about the major challenges regarding water consumption and optimum utlisation.
We are running our cement plant in the water-scarce state of Rajasthan, where we have implemented an efficient water management policy. Recently, water management is becoming a big topic for cement business. It is our prime duty to conserve water and manage it effectively for our next generation. At present, almost all our cement plants are doing their best for optimum utilisation of water.
How do you foresee achieving water positivity and optimising its consumption?
Dependence on only freshwater consumption is now a big question for sustaining business. We are raising our bar for effective utilisation of wastewater in every step of manufacturing. At present, we are 3.6 times water positive and our target to become 5 times water positive in coming years. It will help us to improve our process and to produce cement with less water consumption. We are utilising 100 percent of wastewater and maintaining zero liquid discharge from our all operations. Every drop of water matters. We are actively preventing use of freshwater consumption by optimising processes, implementing AI for monitoring and following 3Rs principle through harvesting and recycling of water.
