The access and availability of clean water affects our lives and changes everything around us. For some people water is readily available when they open their faucets, while some have to travel miles to fetch a few litres and use it sparingly for the next couple of days or even a week. Water covers about 70% of the earth’s surface. With this quantum of water available, it is obvious to think that it is abundant. However, 97% of the earth’s water is saline which is 1,335 million km3, 2% is frozen freshwater which is locked up in glaciers, polar ice caps, soil etc. and is unavailable for use. Thus, only 2,04,000 km3 water is available for consumption which is about 0.5 to 1% of the freshwater available.
Non-uniform distribution of water resources across the globe, erratic climate changes, poor water conservation and management strategies are major reasons for water scarcity. Due to the growing demand and limited availability, India, China, and a few European and African countries are expected to experience water scarcity by 2025.
Water is used mostly for domestic, agriculture and industrial purposes. Globally, freshwater withdrawals in 2017 totalled 3,880 km3, of which India drew 647 km3. Other record mentioned that the water demand of India was 710 km3 in the year 2010. The water demand for industrial activities could be 2 – 16 % of the total demand. Based on one of the references, India utilises approximately 14 km3 for industrial, 48 km3 for domestic, 586 km3 for agricultural purposes. Water demand for agriculture is > 80% of total consumption; hence it is important to increase water efficiency. Data also showed that the demand for industrial applications is expected to increase from 15% to 25% in the next 30 years (refer to the pie chart below), whereas available water resources are limited. It is expected that water scarcity can be physical, where there is not enough water available to meet the demand, or economic, where there is enough water available but not the proper means to produce desirable water quality. In case of water scarcity, industries would be the first to get affected.
One of the simplest solutions is to increase water efficiency. This could be achieved by sustaining Zero Liquid Discharge (ZLD) of wastewater and or using water wisely. Good pre-treatment is the key to successful recycling of water. Hence, industries have to treat wastewater effectively first.
The ongoing technological advancements in manufacturing processes and dynamic product mix are changing the composition of wastewater. Wastewater recycling and reuse could be challenging due to effluent quality, constituents, uncertainty about the effectiveness of conventional treatments and related costs.
Wise reuse of wastewater:
In such circumstances, the emerging trend is to treat wastewater for desired end use. For e.g. treated sewage could be reused for gardening or agriculture by removing organic constituents. The remaining nutrients could act as fertilisers. This approach can not only reduce the costs of recycling but also encourage wise reuse of water.
Adopting a circular economy for water could be another alternative. In a typical dye house, wastewater contains colour and inorganic salts. Water is recovered using a conventional RO (Reverse Osmosis) system, and inorganic salts are concentrated using using Multi-effect Evaporator (MEE) to achieve ZLD. Salts are required in dye baths however, reuse of RO reject is not possible due to the presence of colour. In this case, use of special membranes could separate colour ad salts. These colourless salts could be reused by dye house. Water as well as salts could be reused by adopting the latest technology.
The above solutions appear logical and easy to increase water efficiency. However, those are not easy to achieve due to various reasons. The data for water consumption, water quality, and stage-wise performance of treatment units may not be easily available. This could be due to various reasons such as dynamic variables governing water balance, lack of infrastructure, knowledge gaps, etc. For e.g. industry wanting to optimise water consumption may not have the data for water demand due to older infrastructure. Pricing and variable consumption can make the optimisation complex.
To manage water judiciously, the right information should be made available. Use of digitisation, IoT and AI (Artificial Intelligence) using collected data can help in optimisation and prediction. Thus, it is need of the hour to move towards intelligent decision making system which is possible by leveraging the potential of machine learning and Artificial Intelligence. Utilising data science in wastewater treatment process will enable industries to precisely monitor the usage of water, automate the process and identify faults and rectify it at an early stage. This data can be further utilised to efficiently optimise the process and chemical usages which will result in mitigating the wastage and increasing process reliability.
Industries can adopt different approaches, as mentioned above. Expertise from service or solution providers could be availed to define the best suitable and sustainable solution for a specific case. These services could range from defining water balance, identifying areas for improving water efficiency or arriving at the best suitable treatment scheme. Solution providers can suggest the latest technology for water recovery or implement IoT and AI based solutions for improving water balance.
Human activities and lack of proper water management systems will continue to stress the earth’s accessible freshwater supply. We are rapidly depleting water sources and rely on an unsustainable pace. Hence, shortage of water is certain to happen but preventing and preserving it is important. Efficient industrial wastewater treatment plays a critical role in water quality management. Industries must achieve sustainable wastewater recycling to the maximum extent. Ideally, Zero Liquid Discharge (ZLD) of all liquid streams should be targeted. By integrating conventional and new technologies, a wide range of effluents can be treated effectively, and maximum water recovery can be achieved. Also, utilising upcoming technologies such as artificial intelligence in water treatment sector to have a fully automated intelligent plant will provide control to industries to move towards sustainable and optimum utilisation of water.
Lastly, general water management practices and more water conservation initiatives should be undertaken by industries as well as on an individual level for utilising water wisely.
Nandan Prabhune and Sayali Jadhav,
Innovation and Technology Group,
Thermax Ltd. (Water & Waste Solutions)