In this article we will discuss about the industrial wastewater effluents and their management in Kuwait
N. Al-Awadhi and K. Puskas
Kuwait Institute for Scientific Research P.O. Box 24885, 13109 Safat, Kuwait
Abstract:
Rapid economic growth in Kuwait over the last two decades, has been paralleled by continuous development in industrial activity which is concomitant with the generation of the various pollutants and waste materials. This paper provides detailed assessment of the characteristics of industrial wastewater effluents in Kuwait and also highlights the sources, quantity, and quality of industrial wastewaters.
The paper also gives special reference and considerations to a number of overlooked waste producers from private and public institutions that needs to be assessed in order to have an effective wastewater control in the country.
Introduction:
Rapid economic growth in Kuwait over the last two decades, based on the oil production, has been paralleled by continuous development in industrial activity. This industrial development needs to be structured in such a way that it will fulfil the economic and job- related needs of the country, and yet have minimal adverse impact on the environment and quality of life here.
The generation of the various pollutants and waste materials is normally concomitant with the development of industrial activity, but the adverse effects of the pollutants and waste materials should be eliminated or reduced to acceptable levels through the use of waste reduction and proper treatment technologies, as well as through their optimal reuse or safe disposal.
In this regard, both the generation and treatment of industrial wastewater need special attention in Kuwait, since: the only recipient of any industrial effluent (treated or untreated) is the shallow Gulf water with water intake points to the desalination stations which produce much of the country’s freshwater, and the exploitation of the reuse possibilities for the effluent is necessary in order to maintain water resources and reduce water costs.
Wastewater generation and treatment have been thoroughly studied in the Shuaiba Industrial Area (SIA), one of the largest industrial complexes in the Middle East. The SIA has segregated drainage systems for industrial and municipal wastewater collection and discharge. Since the quantities of these wastewaters are significant and constitute concentrated effluent sources, they are the most valuable wastewater streams for reuse in Kuwait.
This paper will direct attention to wastewater generation in the industries located in smaller industrial areas (e.g., Sabhan) or among commercial and institutional establishments in residential areas. The need for proper handling of these effluents must be emphasized. Many of these industries discharge their effluents often partially treated or untreated into the municipal drainage systems. The proper control of the quality and quantity of these waste streams cannot be maintained under the present conditions.
The potential hazards which can accrue from these effluents has been acknowledged by the management of the Ardiya Municipal Wastewater Treatment Plant, which treats the effluents from the Shuwaikh Industrial Area together with the municipal wastewater. Many operational problems have been reported which have been caused by the toxic industrial effluents, in spite of the fact that the industrial wastewater is less than 20-30 per cent of the total flow rate.
Sampling and analysis of all scattered effluents would be a time-consuming and costly venture. Therefore, emphasis will be placed on the existence of the significant contamination that can result from the wastewater that is generated in the industries and activities that are typical in Kuwait.
The estimations of the pollutants indicate the magnitude of the contamination, but the actual effluent quality depends on the level of wastewater management that is implemented, and the existence and operation of an on- site treatment facility.
In addition to the wastewater generation from the common industrial activities, the oily ballast water that is discharged into the Gulf constitutes a major pollution source for the marine environment, while the oil-contaminated salty water, which is generated during oil mining and production, contaminates the desert soil.
The various contaminants of the industrial effluents and their effect are discussed for better understanding of the magnitude of the environmental impact which can be caused by the industrial effluent, the need for the contaminants treatment and reuse, and the regulation and enforcement needed to reduce the potential risk that is associated with the uncontrolled discharge of the wastewater.
Common Characteristics of Industrial Wastewater Effluents:
In general, industrial manufacturing is the leading source of controllable man-made water pollutants. In addition to the large quantities produced, industrial wastes are also much more likely than other types of waste to contain chemicals that are non-biodegradable, toxic organic substances, and trace elements that must be removed.
When one considers water pollution control and management, it is necessary also to consider, in addition to the nature of the contaminants, how those substances travel through the water systems. As they travel, the contaminants may be degraded by chemical, physical, or biological processes.
They migrate by flow or convection, and disperse throughout the water systems by diffusion and/or mixing. In order to make the best decisions as to how to handle these wastewaters, it is necessary to consider all of these processes and their overall transport.
Only in this way can wise decisions be made as to which pollutants must be removed, and which can remain in the effluent. Computer programs have been developed for this purpose, and are taken advantage of by various industries.
The discharge water from various industries has many of the same problems, plus some additional ones. The types of contaminants are dependent upon the particular industry and the particular process employed.
The contaminants can be classified into three categories:
1. Floating Materials:
Typical floating materials are oils and greases. The fats, oils and greases can be in free form, or physically or chemically emulsified. Their specific quality globule or particle size varies over a wide range.
2. Suspended Matter:
A common example of suspended matter is mineral tailings. Typically, mineral tailings form slime and sludge, which smother purifying microorganisms and ruin fish spawning and breeding grounds. If the suspended matter is organic, it decomposes using the dissolved oxygen, and produces noxious gases and odours.
3. Dissolved Impurities:
Typical dissolved substances are acids, alkalines, chemicals, organic materials, heavy metals and insecticides. In general, they make water undrinkable and destroy aquatic life. The dissolved organic matter can be biodegradable, non-biodegradable, or toxic. For example, phenols, even in very low concentrations (0.001 mg), produce a very objectional taste and odour in water.
They also can accumulate and concentrate their effects through the normal food chain. An unpleasant taste is noticed when eating fish that have lived in water with a phenol concentration of only 0.0001 mg.
Many pollutants are hazardous for human health. Nitrates have been linked to methemoglobinemia and death in infants.
The ingested nitrates can be reduced by microorganisms in the digestive tract to nitrites:
The nitrites can then oxidize the iron atom present in hemoglobin from Fe2+ into Fe3+. The result is a methemoglobin molecule incapable of O2 transport.
Most of the other common substances probably have no major acute effects on human health. Many, however, do have chronic effects. For example, many of the organic substances are carcinogens. Selenium causes bad breath, gastrointestinal problems, and skin discoloration. Sodium and/or potassium are bad for people with certain health problems.
i. Polychlorinated Biphenyls (PCBs):
Polychlorinated biphenyls (PCBs) are a well- known example of a toxic substance that can make its way into the natural water systems. PCBs were used for many years in closed-system electrical applications, such as transformers. The manufacture of new, PCB-containing electrical devices, is now illegal, and equipment of older designs is gradually being replaced.
In spite of the controls now on PCBs, they persist in the environment. They are still used in lubricants, duplicating paper, inks, paints and coatings, adhesives, plastics, and so forth, and many might be imported into Kuwait. The PCBs often leach from landfills, or get into the atmosphere through low-temperature incineration. In addition, accidents, often involving old transformers, contribute appreciably to the number of PCBs in the water systems.
ii. Biodegradable Organics:
A major problem associated with water pollution is the biological oxygen demand, or the BOD. The BOD is the amount of oxygen required to biologically oxidize organic contaminants into carbon dioxide (CO2), and thus, is a measure of the suspended, colloidal, or dissolved organics.
To measure the BOD level, a sample is usually allowed to incubate for 5d. Within this period, about 70-80 per cent of the organic contaminants present are oxidized by the microorganisms present. The choice of units used for BOD reflects the weight of O2; hence, the units are typically pounds or kilograms.
The BOD is important in that the higher the BOD, the higher the organic content of the wastewater, and the more dissolved O2 that will be needed to decompose these organics. A lack of dissolved O2 in the waterways kills off desirable fish.
The presence of organic substances can decrease the dissolved oxygen in another way. The organics, along with the nitrogen and phosphorous, can serve primarily as food for algae. These algae are microscopic, greenish-coloured plants that live in water.
By themselves, they are not harmful to humans (in fact, in limited amounts, they are useful, for they do create O2 for other aquatic life by photosynthesis), but they do become aesthetically unsightly, and constitute both a nuisance and a hazard to other aquatic life when they proliferate.
Their growth rate is dependent upon the conditions of their environment; they do not grow in deep, fast-moving, muddy, or cold waters, but flourish in lakes, ponds and slow-moving streams as long as a sufficient supply of nutrients is available. Thus, nutrients can act as the limiting factor in their growth.
Over-fertilization with nutrients, or eutrophication, can occur naturally (for example, algae growth in the Gulf waters in some seasons). Algae eventually produce a slimy scum and obnoxious odour, they require O2, and hence, can drastically decrease the dissolved O2, supply in water as they decay.
Manufacturing produces large quantities of BOD. The major contributors are the chemical industry, the pulp and paper industry, and the food processing industries (about 20%). Table 1 lists typical BOD and suspended solids levels produced by a variety of industries.
Related to the BOD, and often measured instead, is the Chemical Oxygen Demand (COD). The COD is a measure of the amount of oxygen required to chemically oxidize the contaminants to CO2. The value of the COD is higher than the BOD, because strong oxidants are used that force many substances to react that would not react using biological microorganisms. The COD value thus represents almost 100 per cent of the total organics present. Dissolved sulphites and ferrous compounds, which can act as reducing agents, can also help deplete the O2 supply.
iii. Acidity and Salinity:
The acidity and alkalinity of the industrial effluents can vary from pH 1.0 to pH 12.0. Therefore, another problem often experienced in natural water systems, is the change in the pH of the water. Natural waters now vary in pH from 4.0 to about 9.5. Some of the acidification of the waters occurs naturally.
The pH of the water has a major effect on the type of fish and other aquatic species present. Alkaline streams are usually found in localities where the rock and soil contain CaCO3. The calcium bicarbonate is a source of CO2 for photosynthesis by green plants. Some types of fish can withstand somewhat acidic waters; in fact, pH values as low as about 5 are tolerable. However, under these conditions fish growth is poor.
The Size of the Pollutant Particles:
The size of the pollutant particles also affects their behaviour.
The sizes can be categorized as in Table 2:
The larger particles can absorb and bind various substances on their surfaces, and thus can act as sites to promote bacterial growth, for example. Clays can absorb dissolved organics such as pesticides. These clays can then settle to the bottom of the lake or stream. In this way, the pesticides and other organics become incorporated into the sediments.
Pollutants of concern in wastewater, if reuse is considered, are listed in Table 3 where the different classes of industrial wastewater pollutants are categorized along with measured parameters and potential reuse concerns.
Industrial Wastewater Generation:
The categories of the wastewater generators in Kuwait are as follows:
1. Large industries in the SIA,
2. Various smaller industries in other industrial areas such as Shuwaikh, Sabhan, Sulaibiya, and Shaggaiya,
3. Oil mining and production,
4. Oil transportation (ballast water), and
5. Power and desalination stations.
The flow rates of the industrial wastewater effluents are summarized in Table 4. The main contributors to the total 63,320 m3/d flow rate are the SIA and the Shuwaikh Industrial Area. The estimations for the future flow rate by the year 2005 indicate 20-30 per cent increases. The present treatment system should be improved by segregating the industrial and municipal effluents and introducing efficient on-site or centralized treatment, which can provide wastewater for reuse.
The quantity, quality and the location of the industrial wastewater effluents should be determined for the evaluation of the magnitude of the potential pollution, recommendation of the necessary treatment, and consideration of potential reuse technologies and options that should be used.
i. Shuaiba Industrial Area (SIA):
The industry within this area is based on oil or natural gas or is of a closely related nature. Of significance, in terms of industrial wastewater and pollution loads, are the Petroleum Industries Company (PIC), Kuwait National Petroleum Company (KNPC), Shuaiba Refinery, Mina Abdullah Refinery, Mina Al-Ahmadi Refinery, and the Liquid Petroleum Gas (LPG) Plant.
Each of the industries consumes large volumes of seawater for cooling, and desalinated water for process use and for steam-raising. A large proportion of this water is discharged back into the environment with a relatively unpolluted cooling water or as polluted industrial effluent.
Water is also used for normal domestic and canteen purposes, and is discharged as sanitary wastewater. The primary pollutants in the industrial effluents are ammonia, oil, urea, hydrogen, sulphide and chromium. Currently, the industrial cooling water (seawater) and distilled water-based wastewater effluents are discharged at coastal outfalls.
Although the industries practice some pre-treatment of the industrial effluents, significant loads of harmful pollutants are discharged at these coastal outfalls. Needless to say, in the shallow inshore waters of Shuaiba, an efficient dilution and dispersion of the industrial effluents may not be achieved.
Several other countries have resorted to extending the industrial outfalls deep into the sea, but at Shuaiba, such measures are not likely to be implemented in the near future. The main areas of concern are an increase in nitrogen and oil levels in the ambient seawater affecting the desalinated water, the coastal industries and the marine ecology around Shuaiba, and the possible accumulation of toxic non-biodegradable and persistent xenobiotics in the seawater as well as in the food chains.
Studies have provided data on current and projected mass loads of major pollutants discharged to the sea. Evaluation of the figures on the pollutant loads, in the light of recommended minimum loads for discharge to the sea; indicate that although a slight decrease in some pollutant loads are anticipated, these loads would still be higher than the desirable limits.
The usual arguments for reducing pollution in the inshore waters of Shuaiba are that dilution and dispersion of pollutants are limited, and the effect of the pollutants on seawater quality is deleterious. In view of the limited seawater exchange rate around Shuaiba, the refractory nature of some compounds and the oligotrophic composition of seawater, these potentially harmful pollutants may gradually build up to toxic levels in the seawater, food chains and desalinated water.
The SIA consists of two major sectors with 9 wastewater collection locations as shown in Fig. 1. In the SIA eastern sector, three refineries (the Mina Abdulla, Shuaiba and Ahmadi Refineries), the PIC, the Shuaiba harbour and other smaller industries are the industrial wastewater generators with typical petrochemical and refinery wastewater.
The SIA’s western sector (the New Mina Abdulla Industrial Area) hosts the inorganic, steel, plastic, and paper industries, and its wastewater is characterized mainly by inorganic pollutants. The SIA’s wastewater collection area and discharge systems are shown in Table 5.
Updated information was obtained from the industries, the Shuaiba Area Authority and engineering offices dealing with the implementation of the treatment strategy. A summary of wastewater quantities is presented in Table 6. The three refineries generate 77 per cent and the PIC fertilizer plant 17 per cent of the total flow rate.
All of the other industries generate only 5-6 per cent of the SIA’s total wastewater effluent. Therefore, it can be characterized as petrochemical industrial wastewater. These average values can be changed for the future, especially for the SIA’s western sector, where industrial development is more dynamic.
The estimations for the future wastewater quantities are indicated in Table 7. By 2005, the wastewater generation will be increased by 10-15 per cent according to the industrial growth rate presently estimated. The flow rates include the effluent generated from the major industries (the refineries and PIC), and from the smaller industries in the area as well.
The characteristics of the typical refinery wastewater is demonstrated in Table 8. These values were measured during a comprehensive sampling program in the SIA.
For the treatment of the effluents at a central treatment plant, wastewater streams are combined. The less contaminated streams dilute the effluents with higher contamination. As an advantage of the centralized treatment, the combined effluent quality (Table 9) is better, e.g., the Cr, and CN levels, are less than the irrigation criteria required (therefore, they are not listed).
ii. Other Industrial Areas:
Shuwaikh, Sabhan, and Sulaibiya, were also reviewed to determine and evaluate the wastewater generation in those areas.
In the Shuwaikh Industrial Area, many industries generate various types of industrial wastewaters, which are disposed of into the municipal wastewater collection system and pumped to the Ardiya Wastewater Treatment Plant for treatment.
The flow rates derived from these industries are relatively low, but in view of the great number of the generators, the total flow rate is high. The portion of the industrial streams is 20-30 per cent of the 150,000 m3/d of municipal wastewater.
The Sabhan Industrial Area has several industries generating significant amounts of wastewater. This area is still under dynamic development, and new industries can be established soon. Presently, the soft drinks and dairy industries are the major wastewater generators. The present and the estimated future flow rates are shown in Table 10.
The wastewater from the major generators can be very beneficially reused after treatment for irrigation of the greenery around the area. The wastewater is presently disposed of into the public sewer or into the desert.
In the Sulaibiya and Shaggaya Industrial Areas, the agricultural food industries are the major wastewater generators. Their effluents can be used for irrigation after treatment. The flow rates to be reused are shown in Table. 10.
Special Considerations to Other Waste Generators:
The determination of the wastewater quality by sampling and analysis is not feasible in view of the huge sample amounts and tedious laboratory work that would be required to obtain valuable information on the effluents derived from the great number and variety of the generators and the significant fluctuations in the flow rates that occur therefrom.
Estimations of wastewater quality can be done by evaluating the wastewater generation on the basis of the production and service technologies, and activities involved. A certain production process, service or activity is carried out with similar basic technology using similar raw and auxiliary materials. Therefore, the wastewater quality is also similar.
In the industrial areas in Kuwait, the following waste generators are typical: automotive repair/service shops and stations, food processing plants, hospitals, laboratories, laundries, paint and ink formulation plants, photofinishing shops, steam plants/boilers, institutions, and metal finishing/electroplating plants.
The wastewater generation, estimated wastewater quality, and on-site treatment possibilities are separated into the following sections for each type of industry and institution.
Automotive Repair/Services:
Although the automotive repair industry encompasses many activities, this paper will focus on those shops which could or do generate some type of industrial wastewater harmful to the environment and municipal wastewater treatment systems.
Several types of automotive facilities generate wastewater in Kuwait. Some of the most important generators are the following:
i. Automotive Repair Shops:
Of all the automotive categories which discharge to the sewer, this group is the most problematic. They are the grease and oil dischargers, as well as the heavy metals dischargers. Many of them also use chemicals which can cause their discharge pH to suffer wide swings on both sides of the permitted limits. Individually, their flows do not usually exceed 5 m3/d, but collectively they can represent a meaningful contribution to the collection system.
Machine Shops are primarily involved with specialized manufacturing of metal parts for all types of machinery, of which automotive parts manufacture is but a single activity. The most common wastewater discharge originates from noncontact cooling water for spot welders, air compressors, vapor degreasers, and milling machines. Occasionally, cooling towers may be present, but this is not likely in a small shop.
Many varieties of cutting oils and water-based coolants are used in machining and working with the various metals. These materials can be discharged to the sewer, especially in the smaller shops. In the larger shops all of the oils and coolants could be collected and recycled because it is economically advantageous in addition to their direct discharge being disallowed by most sewer ordinances.
Small amounts are probably routinely discharged to sewers with larger volumes either being hauled away by disposal services or recycled/reclaimed on site. The most common oils found in machine shops are hydraulic fluids, lubricating oils, quenching oils, and cutting oils.
Also, acidic or caustic solutions are occasionally used to clean metal parts. Usually there are post-cleaning rinses associated with these acids and caustics. They may be dead rinses, running rinses, or some combination of the two.
Both the acidic and caustic solutions generally lose their effectiveness more quickly and are discharged more frequently. In every case, the primary concerns are proper handling of any sludge residuals, and ensuring that the liquid portion discharged to the sewer meets the local pH limit.
ii. Engine and Transmission Repair Shops:
Engine and transmission repair shops can be very heavy contributors of grease and oil if no form of pre-treatment is present. The exception is when degreasing is done exclusively with a bake-off method. All of the other degreasing methods—steam cleaning, jet spray, post-solvent rinse or post-caustic (hot tank) rinse—whether used alone or in some combination with each other, all require some type of grease interceptor or clarifier in order to prevent the wholesale discharge of grease and oil to the sewer system. Additionally, when a caustic soak (hot tank) is used, the pH of the discharge effluent is a concern as is the proper handling of the tank bottoms (sludge).
iii. Radiator Shops:
Radiator shops are an example of an industry type that generally has a low volume of wastewater discharge. However, the concentration of the metals present can be extremely high, and the pH can be in the range of 2-12, depending on what operation is being performed. The metals of concern are lead, zinc and copper.
iv. Car Washes:
Full-service car washes generally operate within a discharge volume range of 20 – 200 m3/d at very large or very busy sites. The wide discharge range is due to two main factors: the volume of business and the presence or absence of water reclamation systems.
v. Food Processing:
Food processing includes fruits and vegetables, seafood, slaughterhouses, meat packing and dairy products, and bottling beverages. Food processors, in general, share some common features which make the formation of a generic group for industrial waste discharge evaluation quite plausible.
Mainly, they all share the trait of producing no toxic wastewater per se, but rather their wastewater contains the more conventional pollutants such as grease and oil, and heavy loads of suspended solids. Usually, the wastewater has a high BOD as well. The pH is generally on the caustic side because of the many detergents and caustic cleaning compounds routinely used, but it can be acidic in some instances.
An additional similarity is the across-the-board necessity for some type of steam production system, or other method for sterilization and cleaning procedures. Also needed is some type of cooling or refrigeration system to keep the processed foodstuffs from perishing. They almost always require some type of clarifier, settling vat or other device to remove the bulk of the solids from their effluent.
Only rarely can a food processing site survive without some type of solids removal plan. The exceptions would be a very small operation, or a facility where only beverages are produced.
Also, the pH of the discharge effluent can vary widely from below 5 up-to 12, when acidic disinfecting or cleaning solutions and detergents are utilized. Without equalization tanks, or systems in some cases, it may be necessary to install pH control systems, either in lieu of or in addition to equalization tanks, when flows are large and/or swings are very wide.
vi. Hospitals:
Even though a wide variety of toxic, hazardous and prohibited materials are used by (and discharged by) hospitals, the overall quantity disposed of to the sewer is relatively low, and serious pollution problems are usually non-existent. Nonetheless, a poorly managed facility has the potential to cause serious problems for the sewer department.
These problems could run the gamut from being merely troublesome, if a grease blockage is the concern, to constituting a major issue if concentrated acids, flammables or explosives are involved.
Hospital laboratories usually account for a very low volume of any significant industrial wastes. Their usual effluent is diluted solutions of body fluids in combination with chemical reagents ranging from simple isotonic saline to low-volume, low-concentration cyanide solutions.
However, it is not uncommon for modern-day laboratories to either isolate all of their industrial flow or pass it through an interceptor where acid neutralization can take place, or to individually plumb all laboratory sinks to acid neutralization units. In those institutions where laboratory glassware is still washed (all items that are not disposable), the problematic discharges can originate if chromic or other acid cleaning of any glassware is done.
It is common practice to soak heavily soiled pipettes or other glassware in this type of acid solution. Many times, the employees washing the glass-wares are not as alert to the adverse effects of an acid discharge to the drain as they should be and the glassware washing area, unlike the laboratory proper, is not usually plumbed with acid neutralization units for the discharge.
The toxicology laboratory deserves special mention because it is the only discipline left which may still do the wet-chemistry type of analysis. What this means is that larger volumes of organic solvents could find their way into the sewer from these laboratories. The on-going maintenance of a vivarium entails daily cleaning and disinfection procedures which can generate discharge to the sewer and may also require some type of solids removal equipment.
Standard cleaning and disinfecting chemicals are used in the morgue. The only pollutant of concern leaving this area is most apt to be a biohazard. Such a biohazard would take the form of a disease pathogen entrained in or associated with a discharged body fluid such as blood.
The laundry, central service diet kitchen, and cafeteria generate a common municipal type of wastewater effluent.
vii. Laboratories:
There are many different types of laboratories which use and discharge small amounts of toxic and prohibited materials. Laboratories can be located in medical offices, clinics, private businesses, or hospitals.
Some common types of laboratories which would require industrial waste evaluation are the following:
1. Medical/clinical laboratories,
2. Research laboratories,
3. Toxicology laboratories,
4. Chemistry laboratories,
5. Pathology/histology laboratories,
6. Commercial analytical laboratories, and
7. X-ray laboratories.
Regardless of laboratory type, usually the most important constituents of concern as far as sewer discharge is concerned are:
1. Strong acids, and
2. Potentially combustible, flammable, and/or toxic solvents such as alcohol, benzene, acetone, xylene or ether.
Strong acids can easily be eliminated by the routine installation of marble chip neutralization units at every laboratory sink in a facility or at a large interceptor with the ability to equalize or chemically treat acid wastes.
This coverage should include the glassware washing room where occasional significant discharges, especially of chromic acid, can and do occur. Chromic or other acid is traditionally used to acid clean pipettes and other pieces of laboratory glassware requiring scrupulous cleanliness.
The mitigation of flammable or combustible solvent discharges to the sewer is better addressed by increased efforts at recycling, recovery or product substitution. Fortunately, most laboratories do not use or discharge excessive amounts of flammable or combustible materials to the sewers.
viii. Laundries:
The main type of laundries are industrial laundries which process heavily soiled items like rags, rugs, and uniforms from dirty occupations such as mechanics and labourers; and commercial laundries which handle lightly soiled articles such as bed and table linens and uniforms from clean occupations such as automotive sales personnel and fleet drivers.
Carpets and upholstery cleaners will be considered as commercial laundries, as will diaper services. For discussion purposes, an industrial laundry will be considered to process at least 20 per cent of its total in the form the industrial types of article (e.g., rags, mop heads, rugs, etc.), otherwise its classification will be considered to be commercial.
a. Industrial Laundry:
Because of the type of garments cleaned in an industrial laundry, the facility’s wastewater is typically contaminated with high levels of grease and oil, heavy metals and a variety of organic solvents. In other words, their effluent quality is a direct reflection of the type of work being processed at any given time.
This profile can change from hour to hour and day to day depending on the work schedule and/or work flow. However, it is usually the shop rag component of the business which causes most of their problems with effluent quality.
b. Commercial Laundry:
The typical effluent quality from a strictly commercial laundry is more static than is its industrial counterpart. The usual variations are found in temperature, solids, load and pH level. All of these changes in parameters can be traced back to what was happening in the plant at the time of measurement, i.e., if it was washing, rinsing or performing some other activity.
The typical garments found in commercial laundries include hotel, hospital and other institutional linens, uniforms and laboratory coats from commercial and medical professions.
ix. Paint and Ink Formulation:
While some operations are unique to each site, most paint and ink production plants have many activities that are common to all. Primary among them is equipment cleaning which alone produces the bulk of the wastewater effluent.
Equipment cleaning usually produces two distinct waste streams:
1. Spent solvent from solvent-rinsing operations when oil-based materials are produced.
2. Watery paint washes from the high-pressure water and alkaline cleaning procedures used with latex products.
When properly segregated, both latex water-based paint wastes and solvent wastes can be distilled onsite, and a majority of the materials, including the water, can be rescued. However, distillation residues from solvent clean-up, are still required to be handled as hazardous materials. Also, by further segregating the solvents, the ability to recycle each solvent is improved. Better yet, using only one solvent produces a single waste stream that is even easier to handle.
The primary source of the watery/latex paint waste is the portable tank cleaning operation. The usual sequence is manual cleaning of the tanks with spatulas or scrapers to remove any dried or clinging paint (the preferred procedure is to clean the tanks as soon after use as possible to minimize this step), and rinsing with high-pressure water accompanied by an alkaline cleaning solution.
Normally, if a site produces oil-based products only, no discharge to the sewer is expected. All of their clean-up will be done with solvents, and all of their waste products will be recycled or disposed of as hazardous wastes. On the other hand, if water-based materials are being produced, certain heavy metals can be found in the wastewater.
The most commonly occurring metals are titanium (white paint), chromium (yellow paint), lead (red paint), and mercury (a bactericide). Occasionally, copper can be found if blue ink is produced. It is best to ask for material safety data sheets (MSDs) on all materials where specific formulations are not known and sewerable effluent is being produced.
x. Photofinishing:
All photofinishing activity consists of two main operations: developing film and/or printing paper. Film can be either colour or black and white, and the paper used corresponds to the type of film being processed.
Processing may be accomplished either manually, meaning trays are used for the chemicals and rinsing operations, or via automated processors. The major sources of process wastewater are from waste chemical solutions and waste wash/rinse waters. The pollutants of concern are silver and, to a lesser degree, cyanide and chromium.
The silver is contained in the emulsion of all the processed materials and is present in the wastewater from all such facilities. Cyanide and chromium are present in some bleach solutions in the form of ferricyanide and dichromate compounds, and are present only if these types of bleaches are used.
The pollutants remain the same, but the actual quality and quantity of the wastewater depends on the processing technology, which can be black and white, colour, one-step, or two step processing. The level of automation (from manual to fully automated processes) and the size of the laboratory also influence wastewater generation.
xi. Steam Plant/Boilers:
The principal reason for the existence of a steam power plant or a boiler is for heat generation from oil or natural gas. The end product of the heat is always steam. Often, this steam is used to power turbines for the production of electricity. On a smaller scale, some industrial plants produce enormous quantities of steam simply for process uses (e.g., steam tunnels at commercial/industrial laundries).
The wastes of concern that could originate from steam plants, other than the cooling water per are as follows:
1. Hot, concentrated briny water from boiler and evaporator blow-down (see blow-down section),
2. Concentrated acid and/or alkaline solutions used for boiler system cleaning operations,
3. Cooling tower bleed (see cooling water section),
4. Scrubber water from stack emission control systems (if applicable),
5. Concentrated acid and/or alkaline or briny solutions from the regeneration of ion-exchange softeners, or the demineralization of zeolite softening systems (for feed-water supply), and
6. Miscellaneous testing laboratory wastes.
All boilers must be cleaned periodically, both during operation and at regular intervals. High-pressure boilers must be cleaned an average of once per year. Strong acid and alkaline solutions as well as special cleaning agents (i.e., hydrochloric acid, acetic acid, potassium bromate, ammonia, detergents and phosphates) are used to descale the entire boiler system.
The resultant wastewater generated must be disposed of, and the sewer is the actual choice of means. Since this type of cleaning is relatively frequent, many boiler plants have an acid waste problem if no neutralization system or acid-waste treatment is incorporated into their overall operation plan.
Additionally, the demineralization ion-exchange resin requires acid and alkali regeneration every few days. This waste stream presents a second acid-waste disposal problem or pre-treatment requirement.
xii. Universities, Military Installations and Other Large Institutions:
Evaluation of large, complex institutions like military bases and college campuses can prove to be a difficult and time-consuming experience. The waste streams at these facilities differ from normal sites in that they can have a very diverse assortment of operations, each producing a waste stream needing evaluation on its own merits.
Also, a typical industrial site produces a few relatively high flow, easily identified process streams. This group, on the other hand, is more apt to have several low volume, not so easily identified process streams spread out over a very large area.
Additionally, complexity is added if the responsibility for particular section (e.g., boiler plant, physical plant, grounds, and buildings) is divided among operational groups. In the case of the military, division may occur among various tenant facilities as well as in the operational hierarchy.
Typical operations needing evaluation at a military site, or a college or university campus include the following:
1. Plant operations:
Steam plants, boilers, cogeneration sites cooling towers, chillers, refrigeration units, compressors, vacuum systems, etc.;
2. Maintenance operations:
Various cleaning operations, steam cleaning, and general upkeep of site;
3. Metal finishing:
Foundry, welding electroplating etc.;
4. Metal working:
Machine shops etc.;
5. Auto mechanics and automotive repair;
6. Car washes:
Steam cleaning operations;
7. Carpentry shops:
Woodworking shops;
8. Paint shops:
Paint booths;
9. Photo-printing, graphic arts, and silk-screening;
10. Laundries:
Commercial and/or coin-operated;
11. Hospitals:
Clinics, and dispensaries;
12. Laboratories:
Medical, dental, chemical, biological etc.;
13. Dining/eating facilities, and commissaries;
14. Agriculture:
Landscaping, and horticulture; and
15. Hazardous waste storage/treatment facilities, including radioactive waste storage and/or disposal.
xiii. Metal Finishing/Electroplating:
Among facilities that discharge potential pollutants into the waterways, metal finishing facilities—and particularly electroplaters—account for the majority of metals, cyanides, and toxic organic wastes. Most of these constituents threaten both aquatic and human health.
Typically, concentrations of these materials in untreated discharges from metal finishers are several times greater than that allowed by the regulations. Even when diluted by a large-volume of receiving water, untreated metal finishing discharges can severely degrade water quality.
xiv. Drag-Out:
Contaminants in the discharge from electroplating shops and metal finishing industries originate in several ways. The most common source of pollution is from drag-out, which is plating solution that clings to the work piece and contaminates the rinse water. The amount of pollutants contributed by drag-out is a function of many factors including the design of the racks or barrels carrying the parts to be plated, and the shapes of the parts themselves, as well as the holding time over the process tank prior to rinsing.
xv. Rinse Water:
Large volumes of rinse water are usually needed to clean the drag-out from the work. Rinsing actually serves two purposes; it cleans the part; and it protects subsequent process baths from drag-in contamination. Because of the high flow rates used in conventional rinsing techniques, rinse waters are contaminated with relatively dilute concentrations of process solutions. Typically, rinse waters that follow plating solutions contain between 15 and 100 mg/l of the metal being plated.
xvi. Used/Spent Process Solutions:
Platers discard spent cleaners, acids and bright dips. Although these solutions are not usually made up of metals, it is not uncommon to find cyanide and heavy metals in concentrations of several thousand milligrams per liter in these solutions. This contamination is caused by drag-in from previous process cycles and from metals leached from the work by the process chemicals.
Plating solutions and other process chemicals containing high metal concentrations are rarely discarded. Instead, they are decontaminated or rejuvenated in place, so they are usually not a hazardous waste problem.
xvii. Accidental Spills, Leaks, and Drips of Process Solutions:
These also contribute to effluent contamination.
xviii. Wastewater Generation from the Crude Oil Production:
In addition to crude oil, the stream, from oil wells contains natural gas, solid material and ambient water. The crude oil is separated from the other materials at the gathering stations. The separated solids and water are waste materials, which are disposed of. The separated ambient water is highly saline and contaminated with oil.
The salt content varies by the oil field and even by well, from 1-15 per cent. The oil content depends on the effectiveness of the oil separation system, which consist of mechanical separators and ponds. The oil content of the wastewater can be reduced to 5-20 ppm by an efficient treatment system.
The amount of this wastewater depends on the crude oil production. Presently, the total wastewater generation from all the Kuwaiti oil fields reaches 100,000 m3/d. It is disposed of in desert lagoons where it is evaporated.
The salt and oil remains on the soil’s surface after evaporation. Precise assessment of the amount and quality of this wastewater would be necessary to evaluate its effect, and perhaps to recommend implementation of an improved treatment system.
xix. Wastewater Generation from Crude Oil Transportation:
Wastewater generation at the tanker loading facilities and offshore oil rigs is much less than the oily ballast water, which is disposed of by the tankers into the Gulf. As per the studies carried out so far, the adverse impact of the oily ballast water on the marine environment is significant. Implementation of efficient management and effective treatment is needed.
The tankers are not cleaned after emptying their crude oil. Thus, an amount of oily material remains on the walls and bottom which contaminates the water, put into the tankers to stabilize them on their route back to the oil rigs. The emptying of the ballast water starts before the tanker reaches the Strait of Hormuz and continues to the filling port, contaminating the Gulfs water.
The oil content of the ballast water can reach hundreds of parts per million, and is at least two-thirds of the tanker’s capacity. Technical solutions are available to treat the ballast water. Regulations and enforcement are needed for a satisfactory solution, to be achieved.
xx. Wastewater Generation from the Power Stations:
The power stations in Kuwait are combined with seawater desalination plants, which produce freshwater for all sectors. The wastewater generation of electric power production is discussed in the section on steam plants/boilers. In addition of these effluents, a significant amount of brine is generated during the desalination of seawater.
In the brine, the remaining salt from the desalted water is concentrated. The brine is discharged back into the Gulf. This system is acceptable, and so far problems have not been reported. In the long term, it might cause a continuous increase of the salt content in the Gulfs water and in shallow water, where the seawater current is low, local salt concentrations can reach undesired high levels.
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