Optimisation in Industry

There is incredible competition between the water needs of agriculture, industry, and the growing number of people in our world. There are severe and increasing freshwater shortages in many regions of the world. Indices and maps of water scarcity have been drawn up and there is talk of "water crisis", and predictions of wars to come over water (GROBICKI n.y.).

Industries that produce metals, wood, paper, chemicals, gasoline, oils, and most other products all need water in some part of their production process. Industry is depending on water, much like agriculture and domestic households depend on water. Industrial reliance on water makes it essential to conserve water in every aspect possible and to ensure that water pollution is kept at minimal levels (SCHROEDER 2004).

Annual water volume use by industry is increasing at an enormous rate. According to the UN World Water Development Report, some 300 to 500 million tons of heavy metals, solvents, toxic sludge, and other wastes accumulate each year from industry, most of which is released into the freshwater supply. In some developing countries, 70 % of industrial wastes are dumped into untreated waters where they are contaminating the drinking water. Without any doubt, there are some issues concerning freshwater supplies and industry is a major contributor (SCHROEDER 2004).
In the 50 years from 1950 to 2000, world industrial water withdrawals raised from 200 km³ /year to almost 800 km³ /year, while industrial water consumption has increased from 20 to about 100 km³ /year. The relationship between industrial water withdrawal and industrial growth is not linear. Technological advances lead to water savings as well as water reuse in industry. However, industrial water withdrawals in many developed countries have decreased, while industrial water consumption (which is only a fraction of the total water withdrawal) continues to grow (GROBICKI n.y.).
There is an ever increasing awareness that water resources, which are mobile, renewable natural resources, exist in restricted quantities. Moreover, the available supply can vary considerably during the course of a year, as well as from year to year and from region to region. Hence, a continuous and indefinite expansion of water uses is not possible. A situation of stability in the use of the water that is currently available must be sought. This should be one of the main strategic goals of a long-term water management policy. There is an urgent need to find ways of saving, reusing and recycling water, and to develop methodologies to improve water resource management in Industries (BAU n.y.).

(Adapted from MATANI 2006)

Efficient water use means reducing the demand for water by improving personal habits; reducing wastes; creating an adequate rate schedule; deriving benefits from technical developments and from water management techniques as well as promoting norms and regulations. In short, efficient water use consists of optimising water usage. There is absolute efficiency, to use the least amount of water possible; economic efficiency, which seeks to derive maximum economical benefits; social efficiency, which strives to fulfil the needs of the user community; ecological efficiency, which guarantees natural resource conservation; and institutional efficiency, which qualifies the function of an institution regarding its water-related tasks.

There are various ways in which industry can use water more efficiently. Machinery, industrial processes and related support services require large quantities of water, which can be reduced significantly by introducing water efficient technology. The quality of water required depends not only on the type of industry, the oil or mining industries, for instance, do not require quality as high as the pharmaceutical industry, but also on its use within the process, so that a single industrial plant may need different qualities of water for different processes.

This factsheet provides you an overview of how to save and use water more efficiently in Industries.

(Adapted from CONSERVE WATER GEORGIA 2009; MINISTERY OF THE ENVIRONMENT 1999)

• Build understanding among employees and co-workers. Make them aware of water scarcity issues and the impact of water conservation practise. Conserving water not only saves water, but as well as money, on both operation and production costs.
• Educated employees will be better able to identify problems and think innovative about ways to conserve or reuse water within the company.
• Educate employees on the importance of water conservation and solicit employee suggestions on ways to use water more efficiently. Your company can save more than water with a conservation program.
• Set up a water conservation program. Start by naming a coordinator to develop, implement and oversee a water conservation program.

(Adapted from CONSERVE WATER GEORGIA 2009)

• Read your water metre. By reading your water regularly, you can record your average water consumption. Water metres are generally located near the front of your property. It is suggested that the metres are read and recorded at the beginning of shutdown and at the start of operations. Any water use during shutdown can be attributed to leaks and the leak source should be identified. If your business has multiple buildings or processes, to help you fully understand your water use, you can instal a separate metre at each location.
• Establish a baseline use. Examining your water and sewer bills can help you understand your past water use. To establish a baseline for your average daily consumption, divide your monthly or bi-monthly bill by the number of days in that billing period. This baseline can only be used for comparison if business volumes do not fluctuate. For businesses that have seasonal or growth demands, measuring water use per unit of production is the best way to assess your water efficiency.
• Go beyond the standard information provided by equipment manufactures to investigate the real need of water use
• Identify where and how water is currently being used. Track water use over several weeks.

(Adapted from BEN AIM n.y.; CONSERVE WATER GEORGIA 2009; MCYINTRE 2006)

Many industrial users of fresh water are under growing pressure to reuse and recycle water within their facilities. Their objective is to minimise the amount of water that is discharged, either to a receiving stream or a publicly owned treatment works. The main water efficiency actions in industry are recycling, reuse, and reduction of consumption. Two basic activities are necessary in all three cases: measuring the amount and monitoring the quality of the water.
Three important categories of industrial wastewater reuse are: Cooling water, boiler feed water and process water.

Cooling Water

Cooling towers are one of the most common water recycling technologies in use by industry nowadays. By taking advantage of water’s high heat of evaporation, cooling towers offer effective and relatively inexpensive cooling for a several industrial uses. Companies that rely on once through cooling water may benefit from investigating cooling towers. 2/3 industrial water is used for cooling water (removal of heat). Up to 90% of intake water is used as cooling water in electric power plants or oil refineries. Cooling water is easy to treat, therefore it is easy to reuse. Recycling is also used in washing processes to remove residues or contaminants from products or manufacturing equipment, in which case an appropriate treatment system for such a process must be established.

• Think about eliminating once-through cooling of equipment with municipal water by recycling the water flow to cooling towers or replacing it with air-cooled equipment. High volumes of water can be lost as water vapour while performing the cooling function.
• Use rainwater, dam water or process water to supplement fresh makeup water for cooling towers.
• To avoid overflowing, ensure the float valve and seal of the makeup supply is set correctly.
• Eliminate water lost from wind drift by using baffles and drift eliminators.
• If cooling water cannot be re-circulated, reuse this water in other processes such as cleaning.
  Use air-cooled rather than water-cooled ice making machines.
• Regularly check for leaks in the system.

Boiler Feed Water

Water is used for both heating and cooling. Heating involves the generation of steam in boilers that burn coal, oil, gas or waste products. Boiler freed water is used in various industries for the generation of steam for manufacturing processes. After simple treatment, the water can be reused for various applications.

Process Water

In this system, the outflow from one process whether treated or untreated, can be used in another system requiring a different quality of water. The water used in washing processes can be reused in others requiring a lower quality, transportation of materials, or air purifiers. It is important to identify areas for using the recycled water. Water can be reused for washing floors, sanitary fixtures and irrigation. Check where water treatment is necessary before recycling. Consider waste treatment processes such as wetlands, composting and worm-farms.

Industrial Reuse Options

With appropriate controls, industrial water can be reused on-site, or at an alternative industrial site, for many industrial processes, including the following:

• Material washing
• Process rinse water
• Crate and pallet washing
• Hardstand and vehicle washing
• Industrial fire protection
• In production line
• PH adjustment

Non-Industrial Reuse Options

With appropriate controls, and where risks can be managed to an acceptable level, industrial water may potentially be reused for the following uses, such as:

• Crop irrigation (surface and subsurface)
• Landscape irrigation (surface and subsurface), including irrigation of municipal parks and gardens
• Construction (for example road compaction)
• Dust suppression
• Fire protection
• Toilet flushing at non-residential facilities
• Heating/cooling (air-conditioning) systems
• Commercial car washing facilities or depots
• Commercial laundries or washing machines at non-residential facilities

(Adapted from MATANI 2006)

It is possible to optimise processes, improve operations or modify the equipment or the attitude of users in order to save water. Here it is necessary to calculate the amount of water required by any given process, compare the result with the actual amount used and evaluate options for reducing consumption. Industries which are having adjacent areas such as gardens, sanitary services, etc. have quite good potential of significant reductions. In any industrial efficient water use program, it should be ensured that all personnel have been actively involved.

• Review each process to determine if less water can be used and if the most recent water-saving technology is being employed.
• Identify synergies within different processes regarding hot/cold water and water quality
• Instal timers and pedals to use water only when needed.

(Adapted from CONSERVE WATER GEORGIA 2009)

The easiest way to identify leaks is to know when your use rises above a base level for your operations. Once you have identified that there may be a leak on your property, you need to take steps to locate and repair the leak.
To locate leaks:

• Look for a trend of increased usage that cannot be associated with increased business through sub-metres.
• Conduct regular inspections of equipment or areas where leaks could occur, like pipe-work joints, connexions and fittings. Indications include dampness, rust marks or swelling boards. Significant leaks can often be detected by listening in the absence of other noise.
• Check equipment. Worn, old or poorly maintained equipment can waste significant amounts of water.
• Instal monitoring or sub-metre systems that alert you when excessive flows or reduced pressures breach normal ranges.
• For concealed or subsurface pipe-work, leakage detection companies can employ techniques such as pressure testing, flow monitoring and echo correlation.

(Adapted from U.S.EPA 2000)

• Instal water saving toilets (e.g. low-flush, vacuum, dehydration or composting toilets), adjust flush valves or instal dams on existing toilets.
• Instal faucet aerators and high efficiency shower heads.
• As appliances and equipment wear out, replace them with water-saving models.
• Instal high-pressure, low-volume nozzles on spray washers.
• Use fogging nozzles to cool product.
• Instal in-line strainers on all spray headers; inspect nozzles regularly for clogging.
• Adjust pump cooling and water flushing to the minimum required.
• Choose conveying systems that use water efficiently.
• Replace high-volume hoses with high-pressure, low-volume cleaning systems.
• Replace worn-out equipment with water-saving models.
• Equip all hoses with spring loaded shutoff nozzles.

(Adapted from CONSERVE WATER GEORGIA 2009)

Indoors

• Use brooms, squeegees and dry vacuum cleaners to clean surfaces before washing with water.
• Use washing equipment that has aerated spray nozzles equipped with shut-off valves.
• Fit hoses with high-pressure, low-volume nozzles with shut-off valves.
• Where possible, mop floors instead of hosing.
• Switch from wet carpet cleaning methods, such as steam cleaning, to dry power methods or spot cleaning.

Outdoors

• Sweep parking areas rather than hosing, unless it’s required for health regulations.
• Sweep paved areas.
• Clean plant areas and paths with brooms rather than water.
• Reconsider the need to wash building exteriors or other outside structures.
• Reduce the frequency of cleaning external equipment and floors where possible.
• Change window cleaning schedules from ‘regular’ to ‘as required’ and use squeegees.
• Wash vehicles only when needed.
• Limit the use of high-pressure sprayers, unless they are needed to protect human health and maintain safety.
• Make sure all hoses are fitted with trigger-operated guns.
• For equipment that needs to be cleaned regularly, consider using process water from other areas.
• Use high-pressure nozzles where possible.
• Consider alternative methods of cleaning, such as high-pressure air jets.
• Where possible, wash items in water baths rather than under sprinklers.
• Agitate rinse baths with air or mechanically, to increase rinse water life and efficiency.
• Use scrapers and brooms to remove residue build-up in plant machinery.
• Regularly check that spray nozzles are aimed correctly.

(Adapted from CHERTOW 2008)

Industrial water use has not only a large potential to optimise the water use within one industry, but even more by interlinking different industries with different water type and quality requirements in order to exchange different waters. Symbiosis is a word, which comes from biology and describes intimate living together of two organisms (called symbionts) of different species, for mutual or one-sided benefit. Industrial symbiosis described the same thing but applied to industry: It describes the formation of long-term partnerships and work in solidarity of different industries in order to enhance both environmental performance and competitive capacity by combining two or more economical process.

Industrial symbiosis is part of a new field called industrial ecology. Industrial ecology is principally concerned with the flow of materials and energy through systems at different scales, from products to factories and up to national and global levels. Industrial symbiosis focuses on these flows through networks of businesses and other organisations in local and regional economies as a means of approaching ecologically sustainable industrial development. Industrial symbiosis engages traditionally separate industries in a collective approach to competitive advantage involving physical exchange of materials, energy, water, and/or by-products. The keys to industrial symbiosis are collaboration and the synergistic possibilities offered by geographic proximity.

The term industrial symbiosis was coined in the small municipality of Kalundborg, Denmark, where a well-developed network of dense firm interactions was encountered. The primary partners in Kalundborg, including an oil refinery, a power station, a gypsum board facility, and a pharmaceutical company, share ground water, surface water, wastewater, steam, and fuel, and they also exchange a variety of by-products that become feedstock in other processes.