Key Areas of Action
Water
7. Cleaning Processes and Supplies
Cleaning processes and cleaning supplies are central elements for the functioning of businesses and should therefore be considered as key processes when implementing resource-efficient practices.
Regarding cleaning supplies, the use of green cleaning products (case study 347 “Using environmentally friendly cleaning supplies”) is one option. Cleaning products need to be diluted in water for plants to be able to properly dissolve them after they have been used. Green products require a lot less water to achieve this compared to conventional products.
Other practices focus on the implementation of cleaning-in-place (CIP) processes. Since the 1950s, CIP systems have been reliably used to clean inside surfaces of tanks and pipelines in liquid process equipment to avoid costly downtime associated with lengthy dismantling and cleaning tasks. The technique covers a variety of areas, but its main purpose is to remove solids and bacteria from vessels and pipework. Industries that rely heavily on CIP are those requiring high levels of hygiene, such as food, beverage and pharmaceutical companies. The processes are manual or automated, while a suitable chemical solution is circulated through the tanks, then returned to a central reservoir for reuse. While many existing and older CIP systems can be time-intense and waste large amounts of energy, water and chemicals, innovations now allow plant operators to optimize the process and still meet regulatory safety standards. The case study 98 “Optimisation of cleaning-in-place systems” outlines such concrete improvement options.
Green CIP (case study 67 “Green cleaning in place (CIP)”) is a technology enabling the re-use of caustic soda during parts cleaning in food and drink production. It can lead to significant raw material, energy and water savings as it saves on caustic soda use and reduces wastewater in cleaning processes.
Another resource-efficient practice in this context is high-pressure cleaning (case study 66 “High-pressure cleaning in food and drink industry”) which is used for cleaning multiple types of surfaces (floors, walls, vessels, containers, open equipment and conveyors) and as a rinsing stage following cleaning. The pressure can be adjusted, and cleaning agents are injected into the water, at moderate temperatures of up to 60° C. An important part of the cleaning action is due to mechanical effects.
Impacts and benefits
Switching to improved or green cleaning processes and supplies entail positive impacts on a company’s sustainability performance, and on its resource efficiency which also leads to cost savings. Pressure cleaning, and cleaning water re-use can reduce water and chemical consumption. It also allows for lower waste charges, in particular in terms of discharge of effluent.
In particular, the benefits of using green cleaning products (case study 347 “Using environmentally friendly cleaning supplies”) were assessed by the OEKO Institute in Germany, on the basis of eco-labelled cleaning products (i.e., Blauer Engel certification). The OEKO Institute estimated that 1 000 litres of conventional multipurpose cleaner need 28 000 m3 of water to be dissolved. Environmentally friendly alternatives require 10 000 m3 less water to remove the toxic effects of 1 000 litres of cleaning fluid used, making it not only cheaper but also much better for the environment and more resource efficient. The OEKO Institute further estimated that 1 000 litres of 'green' cleaning liquid costs € 2 less than regular chemical cleaners (€ 23 instead of € 25), representing a 7 % saving.
Furthermore, the use of green CIP processes (case study 67 “Green cleaning in place (CIP)") allows a reduction of cleaning time needed by between 5% and 20% due to faster cleaning, according to the implemented cases, therefore increasing productivity and revenue while reducing material use such as caustic soda.
Technical aspects and implementation
With regard to technical aspects, the case study on green CIP (case study 67 “Green cleaning in place (CIP)”) provides useful information. The core principle is that pipes and tanks are flushed through with hot alkali (instead of cold water) as a first step, resulting in a liquid which is very high in organic matter. The used caustic soda is then passed into the Green CIP process in which a clay-based reagent is used to separate alkali from solids, resulting in a sludge.
Some concerns have been expressed on the more generic CIP processes, namely in the food industry, about the hygiene implications of over-splash and aerosols associated with the use of high-pressure hoses, as projections of caustic soda on skin or in eyes could cause significant damage and work safety implications.
General improvement of cleaning measures can be considered, including for instance:
- Reusing the final rinse water as the first flush in subsequent CIP cycles;
- Reducing CIP flow rates, chemical concentrations or temperatures; optimising the programme based on the needs and therefore adapting water consumption, temperature or pressure;
- Manually removing product residues to ease the load of wet CIP cleaning;
- Reusing chemical solution by returning it to a central cleaning reservoir;
- Reducing labour costs and increasing safety through process automation.
8. Circular Wastewater
The need for pure water is growing, and companies have to pay even more attention to the environmental load of their business by reducing water consumption and environmental contamination. One method to close water cycles are water purification technologies (case study 9 “Closing water cycles”). Besides purification, closing water cycles can also include capturing heating and cooling energy from wastewater streams and utilising it in the production process. Moreover, several examples, such as the BIOFOS waste treatment facility in Denmark (case study 7 “Wastewater is a resource too”), have led the way and showed that wastewater is not waste, but a resource that can be processed to produce energy, nutrients, organic matter and clean, reusable water.
Impacts and benefits
As technologies have improved tremendously over the past years, companies became aware of the valuable resources in wastewater. By optimising the use of wastewater, companies can generate cost savings and decrease the process industry’s impact on the environment.
In terms of cost savings, they can be as high as one million euros per year in a large industrial company, but also SMEs can significantly improve their profitability. Moreover, with the appropriate processing technologies, wastewater can be reutilised several times, tightening the gap between water demand and supply; and purified, so that closed water systems can be used to meet the heating and cooling needs of the industrial process.
The case study 7 “Wastewater is a resource too” reveals that the largest wastewater treatment in Denmark has set the example by recovering gas and energy from wastewater. Sludge from the wastewater is used to produce biogas and the energy balance of BIOFOS, the company that runs the wastewater facility, has been positive since 2014. It means that they sell more energy than they buy in order to operate the wastewater treatment plants. More than 100 000 tonnes of organic waste each year can now be combined with the waste-activated sludge from the local municipality and processed to produce 5.4 megawatts of combined heat and power and over 6 000 tonnes of usable fertiliser instead of being disposed of in local landfills. The overall design of the facility incorporates a mixture of both well-established and novel solutions to maximise recovery of the wastewater resources.
Technical aspects and implementation
The case of industrial purification allows water savings (case study 9 “Closing water cycles”). Disinfection and the removal of heavy chemicals could make the wastewater reusable. Furthermore, wastewater can be pre-purified, e.g., by means of flotation technology. In the method, chemicals and dispersion water are mixed in wastewater, and the air bubbles released from it bring impurities to the surface. The resulting sludge is skimmed from the surface and directed to a sludge processing system. Purified water is released from the flotation basin to the municipal sewage system and from there on to the municipal wastewater plant for final purification.
9. Sustainable Wastewater Treatment
Treating wastewater onsite can be a costly exercise that includes working with hazardous chemicals and metals. By water recycling and wastewater purification, e.g. by using strategic organic chemical cleaning solutions, such as dissolved air flotation (DAF), industries, like the food industry, are able to optimise their wastewater management, reducing the costs of buying the chemicals, the process of using them and the sludge removal and landfilling. That makes the process as a whole more sustainable and environmentally friendly.
Impacts and benefits
Putting a sustainable wastewater treatment in place including water recycling and purification can lead to significant reductions in water bills and bring a range of environmental benefits.
One project treated wastewater in shopping malls, where restaurants increasingly face wastewater compliance issues (case study 7 “Smarter wastewater treatment in shopping malls”). Installing a technology such as DAF units can help eliminate odours and save on logistical costs of having to physically clean and remove the grease build up. Additionally, water treated by DAF can be reused for irrigation or toilet facilities. In the specific case study on wastewater treatment in shopping malls, up to 90% of food court wastewater can be reused for flushing toilets, through implementing a relatively simple technology that doesn’t require major civil works.
Another case in the dairy sector (case study 53 “Sustainable wastewater treatment chemicals in a dairy”), using the same DAF technology, also showed a positive effect on the cost of wastewater treatment. In addition to saving on operation expenses, the industry also reduced its use of hazardous chemicals or metals in the process. By changing the way they treat wastewater, a British dairy was able to reduce the cost of chemical wastewater treatment by 50.000 EUR per year.
Technical aspects and implementation
Dissolved air flotation (DAF) systems are designed to remove total suspended solids (TSS), biochemical oxygen demand (BOD), and oils and greases (O&G) from a wastewater stream. Contaminants are removed using a dissolved air-in-water solution produced by injecting air under pressure into a recycle stream of clarified DAF effluent. This recycle stream is then combined and mixed with incoming wastewater in an internal contact chamber where the dissolved air comes out of the solution in the form of micron-sized bubbles that attach to the contaminants. The bubbles and contaminants rise to the surface and form a floating bed of material that is removed by a surface skimmer into an internal hopper for further handling.
10. Water Saving Processes
Cost of water as a resource and discharge of trade effluent form a significant and growing part of companies’ operating costs. Moreover, organisations and their employees often have little or no idea how much water they use, or the amount of money that could be saved by using water more efficiently. In this context, the case study 60 “Water minimisation in food processes” outlines several simple measures for sites how to eliminate water use.
Because beverage/ food production is a very water-intensive industry, both as an ingredient and used for cleaning, improvements and innovations could be made along the production line and throughout the cleaning processes, in order to save quantities of water, generating cost savings, improving sustainability and mitigating the overall environmental impact of the sector. The example of a German beverage manufacturer shows how to use water through optimised cleaning-in-place technique (case study 385 “Reduced water consumption in beverage production”).
Other good practices include introducing water-saving valves on wash basins (case study 80 “Water-saving valves for a medium sized enterprise”), setting up a closed circuit on a pump (case study 158 “Closed-circuit pump cuts water consumption”), and introducing new membranes that filter out contaminants leading to reduced water use and more effective decontamination (case study 221 “New membrane for ultrafiltration saves water”). In the specific case of an Austrian catering company, installing sensors in the urinals and flow restrictions in office premises led to reduced water consumption (case study 305 “Efficient use of water by installing sensors and flow restrictions, Austrian example”).
Impacts and benefits
While all those different measures lead to significant water savings, it is reported that sites that have not previously tried to save water can reduce their water and effluent bills by up to 30 % by combining low- or no-cost opportunities with longer-term water-saving projects (case study 60 “Water minimisation in food processes”).
Equipment cleaning is a particularly water-intensive process, but case studies have shown that by monitoring water consumption at every stage of the production, including the cleaning, improvements can be made, and water can be saved. For instance, an audit at a meat processing factory in the UK (case study 15 “Water savings in a meat processing plant”) has demonstrated that, by using high-pressure triggered cleaning hoses, substantial water savings could be made, translated into savings of 7.000 m³ of water and 425.000 kWh of energy annually.
A German beverage producer, likewise, has shown that by closely monitoring its cleaning-in-place (CIP), using data management tools, it could optimise its water usage, reducing it by 12% or saving just over 10.000 EUR in water costs per year (case study 385 “Reduced water consumption in beverage production”).
By taking relatively simple measures, such as installing modern infrared sensors in urinals and flow restrictors in offices, the Austrian catering company could reduce its yearly water consumption and gas/power consumption by respectively 240 m³ and 9.000 kWh.
Technical aspects and implementation
In order to reduce water consumption, a company can take a broad range of simple but effective measures, from high-pressured hoses to flow restrictors. By using specialised software and dedicated sensor systems, the water consumption in production and CIP processes can be monitored, analysed and optimised accordingly.
The case study on 60 “Water minimisation in food processes” provides detailed low-to no-cost measures with longer-term water-saving projects, e.g.:
- Turn off taps properly, repair dripping taps immediately;
- Sprays and nozzles regularly maintained;
- Tamper-proof valves fitted on pipes carrying water to specific processes;
- Use a recirculating ring main for the distribution of hot or chilled water;
- Check correct pressure or rate of flow through pipes and other equipment;
- Use water sprays to wash or cool raw materials or product, use high-pressure jets and sprays to wash raw materials;
- Avoid the need to change pre-set positions, consider fitting block valves instead of control valves;
- Wash dirty product in a counter-current flow of water (e.g. washing carrots from the field).
11. Monitoring Water Use
Water is a valuable natural resource that is used in many companies’ essential and non-essential processes. By systematically monitoring consumption levels, companies can reduce water bills and render their use of resources more efficient. Knowing how much water various processes use (case study 58 “Monitoring water consumption in office buildings”), identifying areas of improvements (case study 71 “Monitoring water consumption”), and detecting possible water leaks (case study 302 “Smart monitoring tool cuts water consumption at Irish seafood producer”) are essential steps to start saving this precious resource.
In addition, pilot programs that installed smart meters for gas, water and electricity and provided data-based energy advice have demonstrated significant saving opportunities (case study 401 “Smart meters for SME premises”).
Impacts and benefits
Implementing monitoring systems for a company’s water consumption can lead to water savings and associated costs as several case studies have demonstrated.
In the example of an Irish seafood producer (case study 302 “Smart monitoring tool cuts water consumption at Irish seafood producer”), an online water monitoring system has been set up, which was linked to the council meter and provided live readings. This system allowed water to be monitored remotely. Apart from the environmental benefit of reduced fresh water use, early leak detection through its water monitoring system saved the company € 4 000 annually, reducing water consumption by a staggering 200 m3 annually.
The UK Carbon Trust and the University College Dublin carried out projects with SMEs where smart meters for gas, water, and electricity were installed and benefits were tracked (case study 401 “Smart meters for SME premises”). For instance, a Dutch solar company installed smart water meters which provided regular insight into its consumption and allowed the company to take advantage of lower water prices for non-peak use by better distributing its water consumption throughout the day. Results show that the typical participant in the pilot generated around 1.300 EUR in annual savings by reducing water use by 375 m³, 13.500 kWh of electricity savings and 30.000 kWh of gas. This corresponded to 8,5 tonnes of CO2 savings per SME.
Technical aspects and implementation
While the benefits of understanding the drivers of water consumption and its associated costs have become clear, it can be stated regarding technical implementation that there are different methods of collecting information on water use:
- Bucket and stopwatch approach: By timing how long it takes to fill a bucket (or vessel with a known volume), a flow rate (litres/minute) can be calculated, which can be used to determine water use based on the duration and frequency of each use event;
- Manufacturer and model data: Manufacturers can be contacted directly or search the Internet for information on equipment specifications to determine water use per event;
- Non-invasive ultrasonic flow meters: These can be fitted outside water pipes to track the flow-through rate and determine a water-use profile in target areas or processes;
- Shutdown check: By recording the water meter reading when everyone has left the building and again immediately before work resumes, you can establish how much water is still being used when the site is unoccupied.
Ideally, the data you gather should be stored or recorded electronically in a spreadsheet, for example, which enables you to filter and plot your data on graphs and develop more insight into what is happening.
Additionally, the case study 71 on “Monitoring water consumption” outlines five specific steps in order to identify areas of improvement.
12. Water Saving Mechanism in Toilets
Toilets and urinals can be a major source of wasted water as they typically flush even when they are not being used. An uncontrolled flush can waste around 300 m³ of water per year.
There are a number of technologies that your business could consider to reduce the water that is wasted from flushing urinals, reducing water consumption, sewage and costs, conserving valuable resources and creating fresher sanitary wares.
The refurbishment of sanitary installations can be a first, easy step towards a highly water-efficient company that minimises its fresh water consumption, uses rainwater and recycles second-hand or ‘grey’ water (case study 121 “Refurbishment with water-saving sanitary installations”).
Other case studies present good practices like installing efficient water fittings (case study 11 “Efficient water fittings in guest areas”, or cistern water-savers (case study 48 “Retrofitted water-saving toilet cistern”), and outline other efficiency water saving measures that are relatively easy to implement (case study 353 “Simple water efficiency measures at Henderson of Edinburgh”).
Other options to reduce water consumption for flushing is to install waterless urinals (case study 12 “Waterless urinals”), or low-flush toilets (case study 32 “Low-flush toilet”).
Impacts and benefits
The overall benefit of implementing sanitary water saving technologies or practices is a significant reduction in sanitary water consumption and effluence on a company’s property (more than 40 % by some estimates).
Installing flushing devices, such as low flush toilets with optimised cistern and bowl designs, saves up to 6 litres on each flush (case study 32 “Low-flush toilet”). Waterless urinals in turn significantly lower costs as no wastewater is generated in the sanitary processes, it is easily maintained and 100% odourless and free of bacteria (case study 12 “Waterless urinals”). Dual flushing cuts water use in toilets by around 33 % compared to your average consumption (case study 31 “Cistern displacement or dual flush”).
The technique of cistern displacement uses bags of water, granules or pebbles inserted into the water housing (cistern) to reduce volume. Cistern displacement can save between 0.5 and 2 litres of water per flush. It is a relatively simple retrofit, and has proven to be very efficient where the toilet use is high (e.g. in public buildings) (case study 31 “Cistern displacement or dual flush”).
Technical aspects and implementation
In terms of technical implementation, it can be said that older, more conventional sanitary installations can often easily be replaced by water-saving equipment.
For example, toilets can be equipped with water-saving WC pans and flushing devices. For the valves, an automatic shut-off or full automation is recommended. Depending on the age and type of fixtures in your building, installing these measures should be quite simple. For instance, flow regulators for taps and shower heads require little expertise and changing WC-pans can be done with moderate to low investment.
In the case of waterless urinals, they operate using chemical-impregnated plastic pads, or a spring-loaded trap and a floating layer of oil as barrier. The best thing for the environment is to use the 'chemical-free', waterless option. Prior to installation, waste pipes should be assessed and modified to remove any flow restrictions and thoroughly cleaned during retrofitting. Waterless urinals require specialised cleaning methods with compatible chemicals, and in some cases replacement of the liquid barrier or pad every couple of weeks.
13. Bathroom Water Efficiency in Hotels
The hospitality sector is known and sometimes even stigmatised as a big water consumer, leading to initiatives to engage guests to help water conservation efforts. In addition, efforts to optimise water use during a retrofit are rewarded in terms of sustainability but also of financial benefits. However, retrofitting water systems in existing buildings can be expensive so a cost-benefit analysis of what can be achieved with existing building systems and products and new technology is important, and must be weighed against existing and anticipated use.
In the specific case of a medium-sized hotel in Sussex, installing new water management systems involving building services design, water-efficient plumbing fixtures and fittings, as well as promoting water saving by users proved to be an effective measure (case study 59 “Retrofitting for water efficiency: hotel case study”). Moreover, rainwater or grey-water can be used instead of fresh-water in a number of applications, including toilet flushing, cleaning and irrigation, which reduces fresh- and waste-water volumes and corresponding costs (case study 123 “Using rainwater and grey-water to reduce fresh-water consumption”).
Impacts and benefits
In the case of the hotel in Sussex, an audit revealed that guest rooms, including housekeeping, accounted for over 80 % of total water consumption, and cost analysis showed potential savings of 24 % through investing in a new water management system, with a further 10-15 % savings if WC cisterns and hot/cold basin taps were replaced (case study 59 “Retrofitting for water efficiency: hotel case study”). In addition, water recycling can reduce fresh-water consumption by about 10 %, which has financial and environmental benefits, especially in water-poor regions trying to mitigate the impacts of climate change (case study 123 “Using rainwater and grey-water to reduce fresh-water consumption”).
A large hotel in Birmingham, for example, decided to introduce a run-off system on the property’s roof to divert rainfall into storage tanks. The hotel installed a rainwater catching system, which allowed the hotel to save up to 780 m³ of potable water per year. The simple recycling system has led to reduced fresh water consumption at the property of between 5 % and 10 % (case study 293 “Rainwater usage at city hotel in Birmingham”). In addition, a Spanish hotel introduced an innovative grey-water recycling system, which allowed the hotel to store slightly polluted wastewater, treat it and recirculate it for toilet flushing. The property managed to cut annual water consumption by 20%, with an equivalent reduction of sewage water (case study 350 “Grey-water recycling in Spanish hotels”).
Technical aspects and implementation
There are innovative grey-water recycling systems that allow slightly polluted wastewater to be collected separately from basins and showers, then treated and recirculated for toilet flushing, which significantly reduces potable water consumption. Rainwater can be used in, for example, fire-fighting reservoirs, as cooling water or in heating systems. Rainwater can be collected from roof-tops, filtered and stored in reservoirs. Rainwater also contains no chalk, so less detergent or chemicals are needed when used for cleaning.
While the installation of rainwater and grey-water recycling systems is applicable to all new buildings, retrofitting such systems to existing buildings is expensive and impractical unless the building is undergoing extensive renovation. The reason behind is that grey-water recovery systems require separate pipework and are therefore difficult to retrofit, so new hotels have a distinct advantage in being able to install such systems from the ground up.