Industrial processes release water, heat, and materials as gaseous by-products. These emissions harm the environment and waste resources. However, new technologies may be able to reintroduce these by-products into manufacturing processes, leading to better air quality, more energy efficiency and less freshwater consumed.
Developing such technologies is one of the pressing European challenges, mentioned in the EU Action Plan: ‘Towards Zero Pollution for Air, Water and Soil’. The plan also calls for a change in consumption and production towards zero waste without slowing down economic activities. Europe needs to reduce air pollution by 2030 and bring air quality standards closer to World Health Organization guidelines.
The EU Green Deal chief, Frans Timmermans, states: “the Green Deal aims to build a healthy planet for all. To provide a toxic-free environment for people and planet, we have to act now”. The European Commission aims “to reduce the health impact of air pollution by more than 55% and protect biodiversity from air pollution in an extra 25% of our ecosystems,” he added.
In Europe, industrial activities use about 243,000 cubic hectometres of water every year on average, with some industries gulping down a lot of precious freshwater. Consequently, water-saving innovations will allow freshwater to be used for other purposes such as in local communities, farming, and bio-based industries.
“140,000 cubic hectometres of water are released into the environment – via industrial chimneys – but with impurities or pollutants”
Condensation and recovery
Currently, there are no significant studies, demos, or real applications, to condensate and reuse industrial streams. But the EU funded project, iWAYS, is developing a set of technologies capable of recovering water, acids and heat energy from corrosive exhaust gases to reuse them in the production process. iWAYS systems will then treat discharged water – including the vapours resulted in the condensation obtained while using the Heat Pipe Condensing Economiser – to meet the quality requirements of each industrial process. The recovered heat will be used to reduce primary energy consumption. Additionally, materials from flue gas, such as valuable acids or particulates will be recuperated.
The European Environment Agency states that about 140,000 cubic hectometres of water are released into the environment – via industrial chimneys – but with impurities or pollutants. Luca Montorsi, Professor at the Università degli Studi di Modena e Reggio Emilia, and iWAYS Coordinator, explains that “When water is recovered, materials are too. This is because the condensate water contains materials. For example, in one of our end-user cases – a chemical company – condensation is high in corrosive acid. This is the final product sold to their customers. Recovering the material at this stage of the process will allow a decrease on the load of the current acid recovery units, thus reducing the overall amount of acid waste. With iWAYS solutions, they will decrease the environmental impact and increase their inventory”. This material recovery is particularly important, taking into account that the annual global extraction of materials tripled in the last 50 years and is expected to increase further.
Specially designed Heat Pipe Condensing Economiser composed of new alloys will be able to operate in peak conditions, and to better withstand the corrosive and high particle loaded exhaust. According to Professor Jouhara: “iWAYS is a unique and pioneering approach because it addresses streams that are currently impossible to exploit due to the harsh conditions of the process or the corrosive exhaust gases.”
Additional steps for sustainability
According to the European Environment Agency, the growth of the global economy in the past five decades has come at a massive cost to the environment. Innovation is the biggest tool to bridge capability gaps and develop new sustainable processes.
“the systems developed were successful in recovering the waste heat while addressing difficult and abrasive environments”
In the case of iWAYS, two previous innovation projects paved the way for the current research: “Design for Resource and Energy Efficiency in Ceramic Kilns” (DREAM) and “Heat Pipe Technology for Thermal Energy Recovery in Industrial Applications” (ETEKINA). For those projects, the aim was to recover waste heat from high temperature exhausts from burners. The systems developed were successful in recovering the waste heat while addressing difficult and abrasive environments. DREAM and ETEKINA (still an ongoing project) deal with the waste heat and their research has facilitated the recovery of the latent element in the form of water vapour.
In iWAYS the Heat Pipe Condensing Economiser will be validated in the context of holistic plant energy and resource management, which is quite beyond the scope of the previous projects. As mentioned previously, the Heat Pipe Condensing Economiser will be balanced and optimised in terms of operation to work alongside water treatment and material recovery.
The project will apply unique solutions in three use cases or demo sites. One industry is related to chemicals, another to steel-tubes and one to ceramics. Each use case was selected for a specific reason, to test every solution.
The chemical company was selected to demonstrate the highly corrosive resistance of the alloys that are being selected, and the ability of heat pipes to condense these acids safely. The wastewater treatment system will also be tested to remove all the pollutant and reuse it in the process. The quality of the water to be reused in the process needs to be high. With the current filtration system used at the company, the water cannot be reused and is currently being discharged into the sea.
The steel tube production company was selected for the wastewater treatment system that will be put in place. Like the entire steel sector, a large amount of water is consumed for steel cooling and this steam is usually discharged. The Heat Pipe Condensing Economiser will be a valuable alternative for condensing and recovering the steam. The water treatment side of the project will also focus on the recovery of water from sludge that is currently being treated off site. Eliminating this sludge will present a huge benefit for the company.
The ceramic company was selected for its great potential to recover large amounts of water during the spray drier process. As the exhaust exits the spray drier, there will also be a large quantity of particulates in the stream. To be reused, the quality of the water needs to be close that of fresh water, which will raise another challenge.
Water efficiency in every area
As mentioned before, industries are major users of freshwater, for processing, washing, diluting, heating, cooling, and transporting products. Industries account for about 40% of total water consumption. Since freshwater is a scarce resource, breakthrough innovations are needed to recycle water.
Water efficiency is one of iWAYS targets. This will be achieved by three means: reduction of freshwater consumption and recovery of water from humid exhaust gases; the treatment of the condensed water; and the study of alternative water sources and modifications to the productive processes.
Regarding the reduction of freshwater consumption and the recovery of water, savings of 30% to 60% are expected in the use cases. For example, in the steel pipe industry, water is used mainly in the cooling process and in the degreasing procedures. The wastewater is treated and reused in the processes to reduce the freshwater consumption. Nevertheless, during the cooling treatment of the red-hot pipes, a significant amount of water evaporates. With iWAYS technologies more evaporated water will be recovered. That water will then be treated and recycled back in the cooling process. Similarly, around 95% of the water included in the sludge will be recovered and treated to be recycled in the plant.
In the ceramic industry, up to 50% of the freshwater is expected to be saved. In the manufacturing process, the use of freshwater has different applications. In particular, a large amount of water is employed for raw material grinding processes. The water is released to the atmosphere during the spray drying process that produces the ceramic powder while the material for the tile is forming. The water employed in the grinding and spray drying processes is then disposed of through the gaseous exhaust stream. iWAYS technologies will enable the water content of the exhaust gases to be recovered, treated and recycled back.
Regarding the second means, treatment of the condensed water necessary to recycle it, different technologies will be used: photocatalytic nano-filtration, ultrafiltration and evaporative crystallisation. Also, some issues affecting commercial technologies such as reverse osmosis and membrane distillation will be addressed.
In addition, iWAYS will provide an extensive analysis of the industrial production sites. Operational changes of cooling water operations by allowing cooling water to increase in temperature, can substantially decrease cooling water flows at the production sites. Additionally, those changes in the water temperature will also decrease electrical energy use.
“by achieving energy efficiency and decreasing the freshwater consumption, the overall production cost will be reduced”
In relation with the study of alternative water sources and modifications to the productive processes, iWAYS will integrate and adapt to every use case, and alternative fresh water sources, such as surface run-off, and also implement balancing reservoirs.
The application of all three measures will reduce brine volumes and wastewater discharges from industrial manufacturing. iWAYS results will thus contribute to the competitiveness of European industry. Most of the production costs are related to the energy necessary to transform raw materials into a commercial product. By achieving energy efficiency and decreasing the freshwater consumption, the overall cost will be reduced. Therefore, the plants can benefit not only from having a competitive advantage, but also adhering to the energy efficiency directives and meeting the goals of the European Green Deal.
Water close loop
A common feature of the three use cases is the introduction of water closed loops. The aim is near-zero discharge using these close-loop systems. iWAYS will create and validate technologies and designs to recover water from the gaseous waste stream in the ceramics, chemicals, and steel industries, which will represent a fundamental step towards new water closed-loops.
Such closed loops would significantly reduce the use of freshwater and improve water availability in water catchment areas, as outlined in the Water Framework Directive, for other purposes.
Furthermore, the replicability study in the project will demonstrate that this technology can be applied to a large number of industrial processes, expanding the impacts of the project to a wide range of sectors, such as cement, aluminium and non-ferrous material, food, and paper-pulp.
For iWAYS’ researchers, every chimney with a white plume is a water waste stream waiting to be addressed. The recovery of heat from these exhaust streams, and the condensation and recovery of the water and materials, are often not cost-effective due to low temperature, flow composition or particles load – but all of that can be solved by using heat exchangers.
The replicability is estimated in two directions: cross-sectoral (the variety among the existing use cases will serve as proof that the solutions could be easily applied in a multitude of sectors) and the regional transferability, as the innovation hubs evolve, additional industries can make use of geographical areas, referred to as “followers”.
The replicability study demonstrates that the iWAYS solutions can be applied to a large number of industrial processes, expanding the impacts of the project to a wide range of sectors. The identification and quantification of waste streams will generate resource potential profiles, which will in turn be absorbed by another industry.
The rollout of this model will be supported by the partners in other locations, even if the original use cases are located in Sweden, Italy and Spain.
Given the highly adaptable solutions and significant advantages, and the experience of the partners involved in this international group, the potential for replicability of these solutions is immense. It is expected that the results could be applied in almost 19 installations. The iWAYS project lasts four years and is expected to end in November 2024.