Industrial water treatment

Last updated March 16, 2024

There are many uses of water in industry and, in most cases, the used water also needs treatment to render it fit for re-use or disposal. Raw water entering an industrial plant often needs treatment to meet tight quality specifications to be of use in specific industrial processes. Industrial water treatment encompasses all these aspects which include industrial wastewater treatment, boiler water treatment and cooling water treatment.

Overview

Water treatment is used to optimize most water-based industrial processes, such as heating, cooling, processing, cleaning, and rinsing so that operating costs and risks are reduced. Poor water treatment lets water interact with the surfaces of pipes and vessels which contain it. Steam boilers can scale up or corrode, and these deposits will mean more fuel is needed to heat the same amount of water. Cooling towers can also scale up and corrode, but left untreated, the warm, dirty water they can contain will encourage bacteria to grow, and Legionnaires' disease can be the fatal consequence. Water treatment is also used to improve the quality of water contacting the manufactured product (e.g., semiconductors) and/or can be part of the product (e.g., beverages, pharmaceuticals). In these instances, poor water treatment can cause defective products.^{[ citation needed ]}

In many cases, effluent water from one process can be suitable for reuse in another process if given suitable treatment. This can reduce costs by lowering charges for water consumption, reduce the costs of effluent disposal because of reduced volume, and lower energy costs due to the recovery of heat in recycled wastewater.

Objectives

Industrial water treatment seeks to manage four main problem areas: scaling, corrosion, microbiological activity and disposal of residual wastewater. Boilers do not have many problems with microbes as the high temperatures prevent their growth.

Scaling occurs when the chemistry and temperature conditions are such that the dissolved mineral salts in the water are caused to precipitate and form solid deposits. These can be mobile, like a fine silt, or can build up in layers on the metal surfaces of the systems. Scale is a problem because it insulates and heat exchange becomes less efficient as the scale thickens, which wastes energy. Scale also narrows pipe widths and therefore increases the energy used in pumping the water through the pipes.

Corrosion occurs when the parent metal oxidises (as iron rusts, for example) and gradually the integrity of the plant equipment is compromised. The corrosion products can cause similar problems to scale, but corrosion can also lead to leaks, which in a pressurised system can lead to catastrophic failures.

Microbes can thrive in untreated cooling water, which is warm and sometimes full of organic nutrients as wet cooling towers are very efficient air scrubbers. Dust, flies, grass, fungal spores, and others collect in the water and create a sort of "microbial soup" if not treated with biocides. Many outbreaks of the deadly Legionnaires' Disease have been traced to unmanaged cooling towers, and the UK has had stringent Health & Safety guidelines concerning cooling tower operations for many years as have had governmental agencies in other countries.

Certain processes like tanning and paper making use heavy metals such as Chrome for tanning. Although most is used up but some amount remains and gets carried away with water. The presence in drinking water is toxic when consumed so even the smallest amount must be removed.^{[ citation needed ]}

Disposal of residual industrial wastewaters

Disposal of residual wastewaters from an industrial plant is a difficult and costly problem.^[1] Most petroleum refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into sewage treatment plants or into rivers, lakes or oceans.^[2]

Processes

Two of the main processes of industrial water treatment are boiler water treatment and cooling water treatment. A large amount of proper water treatment can lead to the reaction of solids and bacteria within pipe work and boiler housing. Steam boilers can suffer from scale or corrosion when left untreated. Scale deposits can lead to weak and dangerous machinery, while additional fuel is required to heat the same level of water because of the rise in thermal resistance. Poor quality dirty water can become a breeding ground for bacteria such as Legionella causing a risk to public health.

Corrosion in low pressure boilers can be caused by dissolved oxygen, acidity and excessive alkalinity. Water treatment therefore should remove the dissolved oxygen and maintain the boiler water with the appropriate pH and alkalinity levels. Without effective water treatment, a cooling water system can suffer from scale formation, corrosion and fouling and may become a breeding ground for harmful bacteria. This reduces efficiency, shortens plant life and makes operations unreliable and unsafe.^[3]

Boiler water treatment

Boiler water treatment is a type of industrial water treatment focused on removal or chemical modification of substances potentially damaging to the boiler. Varying types of treatment are used at different locations to avoid scale, corrosion, or foaming. External treatment of raw water supplies intended for use within a boiler is focused on removal of impurities before they reach the boiler. Internal treatment within the boiler is focused on limiting the tendency of water to dissolve the boiler, and maintaining impurities in forms least likely to cause trouble before they can be removed from the boiler in boiler blowdown. Deaerator is used to reduce oxygen and nitrogen in boiler feed water applications.

Cooling water treatment

Water cooling is a method of heat removal from components of machinery and industrial equipment. Water may be a more efficient heat transfer fluid where air cooling is ineffective. In most occupied climates water offers the thermal conductivity advantages of a liquid with unusually high specific heat capacity and the option that of evaporative cooling. Low cost often allows rejection as waste after a single use, but recycling coolant loops may be pressurized to eliminate evaporative loss and offer greater portability and improved cleanliness. Unpressurized recycling coolant loops using evaporative cooling require a blowdown waste stream to remove impurities concentrated by evaporation. Disadvantages of water cooling systems include accelerated corrosion and maintenance requirements to prevent heat transfer reductions from biofouling or scale formation. Chemical additives to reduce these disadvantages may introduce toxicity to wastewater. Water cooling is commonly used for cooling automobile internal combustion engines and large industrial facilities such as nuclear and steam electric power plants, hydroelectric generators, petroleum refineries and chemical plants.

Technologies

Advancements in water treatment technology have affected all areas of industrial water treatment. Although mechanical filtration, such as reverse osmosis, is widely employed to filter contaminants, other technologies including the use of ozone generators, wastewater evaporation, electrodeionization and bioremediation are also able to address the challenges of industrial water treatment.

Ozone treatment is a process in which ozone gas is injected into waste streams as a means to reduce or eliminate the need for water treatment chemicals or sanitizers that may be hazardous, including chlorine.^{[ citation needed ]}

Chemical treatment

Chemical treatments utilize the additive of chemicals to make industrial water suitable for use or discharge. That includes processes like chemical precipitation, chemical disinfection, Advanced oxidation process (AOP), ion exchange, and chemical neutralization.^[4] AOPs are attractive in the treatment of hazardous wastewater due to its high oxidation potential and degradation performance.^[5]^[6] In AOPs, oxidants like Fenton's reagent, Ozone or Hydrogen peroxide are introduced in the wastewater to degrade harmful substances in industrial water for discharge.

Physical treatment

Physical treatment involves the separation of solids form industrial wastewater either through Filtration or Dissolved air flotation. Filtration involves the use of Membrane or filters such as mechanical filters like sand filtration etc to achieve solid-liquid separation. Whereas for Dissolved air flotation,

pressurized air is pumped into the wastewater. The pressurized air then forms small bubbles which adhere to the suspended matter causing them to float to the surface of the water where they can be removed by a skimming device or an overflow.^[7]

Biological treatment

Biological treatment is needed to treat wastewater containing biodegradable elements. It is commonly used in municipal and industrial wastewater management facilities and usually consists in adding common bacteria and other microbes, mostly environmentally friendly, to treat the water. It is a sustainable practice that has been successful for over a century.

Slow sand filters use a biological process to purify raw water to produce potable water.^[8] They work by using a complex biological film that grows naturally on the surface of sand. This gelatinous biofilm called the hypogeal layer or Schmutzdecke is located in the upper few millimetres of the sand layer. The surface biofilm purifies the water as it flows through the layer, the underlying sand provides a support medium for the biological treatment layer.^[9] The Schmutzdecke consists of bacteria, fungi, protozoa, rotifera and a range of aquatic insect larvae. As the biofilm ages, more algae may develop and larger aquatic organisms including bryozoa, snails and Annelid worms may be present. As water passes through the hypogeal layer, particles of matter are trapped in the mucilaginous matrix and soluble organic material is adsorbed. The contaminants are metabolised by the bacteria, fungi and protozoa.^[8]

Slow sand filters are typically 1–2 metres deep, and have a hydraulic loading rate of 0.2–0.4 cubic metres per square metre per hour.^[9] Filters lose their performance as the biofilm thickens and reduces the rate of flow. The filter is refurbished by removing the biofilm and a thin upper layer of sand. Water is decanted back into the filter and re-circulated to enable a new biofilm to develop. Alternatively wet harrowing involves stirring the sand and flushing the biolayer through for disposal.^[9]

Ultraviolet irradiation

Ultraviolet (UV) disinfection technology has been a common water treatment technology in the past two decades due to its ability to provide disinfected water without the use of harmful chemicals. The UV-C portion represents wavelengths from 200 nm - 280 nm which is used for disinfection. UV-C photons penetrate cells and damage the nucleic acid, rendering them incapable of reproduction, or microbiologically inactive.^[10]

Process water treatment technology

Process water is water that is used in a variety of manufacturing operations, such as: coating and plating; rinsing and spraying; washing, etc. Municipal and ground water often contain dissolved minerals which make it unsuitable for these processes because it would affect product quality and/or increase manufacturing costs. A proper incoming water treatment system can remedy these issues and create the right water conditions for specific industrial processes.^{[ citation needed ]}

Related Research Articles

<span class="mw-page-title-main">Filtration</span> Process that separates solids from fluids

Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles. Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms.

Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption, but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.

Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.

Wastewater treatment is a process which removes and eliminates contaminants from wastewater and converts this into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes. The treatment process takes place in a wastewater treatment plant. There are several kinds of wastewater which are treated at the appropriate type of wastewater treatment plant. For domestic wastewater, the treatment plant is called a Sewage Treatment. For industrial wastewater, treatment either takes place in a separate Industrial wastewater treatment, or in a sewage treatment plant. Further types of wastewater treatment plants include Agricultural wastewater treatment and leachate treatment plants.

In the oil industry, waterflooding or water injection is where water is injected into the oil reservoir, to maintain the pressure, or to drive oil towards the wells, and thereby increase production. Water injection wells may be located on- and offshore, to increase oil recovery from an existing reservoir.

<span class="mw-page-title-main">Biofilter</span> Pollution control technique

Biofiltration is a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, and microbiotic oxidation of contaminants in air. Industrial biofiltration can be classified as the process of utilizing biological oxidation to remove volatile organic compounds, odors, and hydrocarbons.

A constructed wetland is an artificial wetland to treat sewage, greywater, stormwater runoff or industrial wastewater. It may also be designed for land reclamation after mining, or as a mitigation step for natural areas lost to land development. Constructed wetlands are engineered systems that use the natural functions of vegetation, soil, and organisms to provide secondary treatment to wastewater. The design of the constructed wetland has to be adjusted according to the type of wastewater to be treated. Constructed wetlands have been used in both centralized and decentralized wastewater systems. Primary treatment is recommended when there is a large amount of suspended solids or soluble organic matter.

Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater may be reused or released to a sanitary sewer or to a surface water in the environment. Some industrial facilities generate wastewater that can be treated in sewage treatment plants. Most industrial processes, such as petroleum refineries, chemical and petrochemical plants have their own specialized facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the regulations regarding disposal of wastewaters into sewers or into rivers, lakes or oceans. This applies to industries that generate wastewater with high concentrations of organic matter, toxic pollutants or nutrients such as ammonia. Some industries install a pre-treatment system to remove some pollutants, and then discharge the partially treated wastewater to the municipal sewer system.

<span class="mw-page-title-main">Fouling</span> Accumulation of unwanted material on solid surfaces

Fouling is the accumulation of unwanted material on solid surfaces. The fouling materials can consist of either living organisms (biofouling) or a non-living substance. Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system, or plant performing a defined and useful function and that the fouling process impedes or interferes with this function.

Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources for drinking purposes. Their main function is to eliminate pathogens, and often also of suspended solids and some unpalatable or toxic compounds.

Secondary treatment is the removal of biodegradable organic matter from sewage or similar kinds of wastewater. The aim is to achieve a certain degree of effluent quality in a sewage treatment plant suitable for the intended disposal or reuse option. A "primary treatment" step often precedes secondary treatment, whereby physical phase separation is used to remove settleable solids. During secondary treatment, biological processes are used to remove dissolved and suspended organic matter measured as biochemical oxygen demand (BOD). These processes are performed by microorganisms in a managed aerobic or anaerobic process depending on the treatment technology. Bacteria and protozoa consume biodegradable soluble organic contaminants while reproducing to form cells of biological solids. Secondary treatment is widely used in sewage treatment and is also applicable to many agricultural and industrial wastewaters.

Sewage sludge treatment describes the processes used to manage and dispose of sewage sludge produced during sewage treatment. Sludge treatment is focused on reducing sludge weight and volume to reduce transportation and disposal costs, and on reducing potential health risks of disposal options. Water removal is the primary means of weight and volume reduction, while pathogen destruction is frequently accomplished through heating during thermophilic digestion, composting, or incineration. The choice of a sludge treatment method depends on the volume of sludge generated, and comparison of treatment costs required for available disposal options. Air-drying and composting may be attractive to rural communities, while limited land availability may make aerobic digestion and mechanical dewatering preferable for cities, and economies of scale may encourage energy recovery alternatives in metropolitan areas.

Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There are a high number of sewage treatment processes to choose from. These can range from decentralized systems to large centralized systems involving a network of pipes and pump stations which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter from sewage, using aerobic or anaerobic biological processes. A so-called quarternary treatment step can also be added for the removal of organic micropollutants, such as pharmaceuticals. This has been implemented in full-scale for example in Sweden.

Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distributions. RO can remove dissolved or suspended chemical species as well as biological substances, and is used in industrial processes and the production of potable water. RO retains the solute on the pressurized side of the membrane and the purified solvent passes to the other side. It relies on the relative sizes of the various molecules to decide what passes through. "Selective" membranes reject large molecules, while accepting smaller molecules.

Copper zinc water filtration is a high-purity brass water filtration process that relies on the redox potential of dissolved oxygen in water in the presence of a zinc anode and copper cathode. It uses dissolved impurities within water as constituent substrate, which are reduced to more physiologically inert compounds.

Raw water is water found in the environment that has not been treated and does not have any of its minerals, ions, particles, bacteria, or parasites removed. Raw water includes rainwater, ground water, water from infiltration wells, and water from bodies like lakes and rivers.

Ozonia is a multinational water treatment equipment manufacturer headquartered in Zürich, Switzerland.

A mixed oxidant solution (MOS) is a type of disinfectant that has many uses including disinfecting, sterilizing, and eliminating pathogenic microorganisms in water. An MOS may have advantages such as a higher disinfecting power, stable residual chlorine in water, elimination of biofilm, and safety. The main components of an MOS are chlorine and its derivatives, which are produced by electrolysis of sodium chloride. It may also contain high amounts of hydroxy radicals, chlorine dioxide, dissolved ozone, hydrogen peroxide and oxygen from which the name "mixed oxidant" is derived.

Pile Cloth Media Filtration is a mechanical process for the separation of organic and inorganic solids from liquids. It belongs to the processes of surface filtration and cake filtration where, in addition to the sieve effect, real filtration effects occur over the depth of the pile layer. Pile Cloth Media Filtration represents a branch of cloth filtration processes and is used for water and wastewater treatment in medium and large scale. In Pile Cloth Media Filtration, three-dimensional textile fabrics are used as filter media. During the filter cleaning of the pile layer the filtration process continues and is not interrupted.

References

↑ Tchobanoglous, G.; Burton, F.L.; Stensel, H.D.; Metcalf & Eddy, Inc. (2003). Wastewater Engineering (Treatment Disposal Reuse) (4th ed.). McGraw-Hill. ISBN 978-0-07-041878-3.{{cite book}}: CS1 maint: multiple names: authors list (link)
↑ Beychok, Milton R. (1967). Aqueous Wastes from Petroleum and Petrochemical Plants (1s ed.). John Wiley & Sons. LCCN 67019834.
↑ Cicek, V. (2013). "Corrosion and corrosion prevention in boilers". Cathodic protection: industrial solutions for protecting against corrosion. Hoboken, New Jersey: John Wiley & Sons. ISBN 9781118737880.
↑ Pal, Parimal (2017-01-01), Pal, Parimal (ed.), "Chapter 2 – Chemical Treatment Technology", Industrial Water Treatment Process Technology, Butterworth-Heinemann, pp. 21–63, doi:10.1016/B978-0-12-810391-3.00002-3, ISBN 9780128103913
↑ Cai, Q.Q.; Lee, B.C.Y.; Ong, S.L.; Hu, J.Y. (February 2021). "Fluidized-bed Fenton technologies for recalcitrant industrial wastewater treatment–Recent advances, challenges and perspective". Water Research. 190: 116692. doi:10.1016/j.watres.2020.116692. PMID 33279748. S2CID 227523802.
↑ Hansson, Henrik; Kaczala, Fabio; Amaro, Alexandre; Marques, Marcia; Hogland, William (2015-07-01). "Advanced Oxidation Treatment of Recalcitrant Wastewater from a Wood-Based Industry: a Comparative Study of O3 and O3/UV". Water, Air, & Soil Pollution. 226 (7): 229. Bibcode:2015WASP..226..229H. doi:10.1007/s11270-015-2468-5. ISSN 1573-2932. S2CID 92701177.
↑ Wong, Joe (2013). "Dissolved Air Flotation". Water World. Retrieved 26 June 2020.
1 2 SSWM University. "Slow sand filtration". SSWM University. Retrieved 26 June 2020.
1 2 3 B. Sizirici Yildiz (2012). "Slow sand filtration". doi:10.1533/9780857096463.3.406.{{cite journal}}: Cite journal requires |journal= (help)
↑ Meulemans, C. C. E. (1987-09-01). "The Basic Principles of UV–Disinfection of Water". Ozone: Science & Engineering. 9 (4): 299–313. doi:10.1080/01919518708552146. ISSN 0191-9512.

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[1] Tchobanoglous, G.; Burton, F.L.; Stensel, H.D.; Metcalf & Eddy, Inc. (2003). Wastewater Engineering (Treatment Disposal Reuse) (4th ed.). McGraw-Hill. ISBN 978-0-07-041878-3.{{cite book}}: CS1 maint: multiple names: authors list (link)

[2] Beychok, Milton R. (1967). Aqueous Wastes from Petroleum and Petrochemical Plants (1s ed.). John Wiley & Sons. LCCN 67019834.

[3] Cicek, V. (2013). "Corrosion and corrosion prevention in boilers". Cathodic protection: industrial solutions for protecting against corrosion. Hoboken, New Jersey: John Wiley & Sons. ISBN 9781118737880.

[4] Pal, Parimal (2017-01-01), Pal, Parimal (ed.), "Chapter 2 – Chemical Treatment Technology", Industrial Water Treatment Process Technology, Butterworth-Heinemann, pp. 21–63, doi:10.1016/B978-0-12-810391-3.00002-3, ISBN 9780128103913

[5] Cai, Q.Q.; Lee, B.C.Y.; Ong, S.L.; Hu, J.Y. (February 2021). "Fluidized-bed Fenton technologies for recalcitrant industrial wastewater treatment–Recent advances, challenges and perspective". Water Research. 190: 116692. doi:10.1016/j.watres.2020.116692. PMID 33279748. S2CID 227523802.

[6] Hansson, Henrik; Kaczala, Fabio; Amaro, Alexandre; Marques, Marcia; Hogland, William (2015-07-01). "Advanced Oxidation Treatment of Recalcitrant Wastewater from a Wood-Based Industry: a Comparative Study of O3 and O3/UV". Water, Air, & Soil Pollution. 226 (7): 229. Bibcode:2015WASP..226..229H. doi:10.1007/s11270-015-2468-5. ISSN 1573-2932. S2CID 92701177.

[:0-7] Wong, Joe (2013). "Dissolved Air Flotation". Water World. Retrieved 26 June 2020.

[:1-8] 1 2 SSWM University. "Slow sand filtration". SSWM University. Retrieved 26 June 2020.

[:2-9] 1 2 3 B. Sizirici Yildiz (2012). "Slow sand filtration". doi:10.1533/9780857096463.3.406.{{cite journal}}: Cite journal requires |journal= (help)

[10] Meulemans, C. C. E. (1987-09-01). "The Basic Principles of UV–Disinfection of Water". Ozone: Science & Engineering. 9 (4): 299–313. doi:10.1080/01919518708552146. ISSN 0191-9512.

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