Industrial Wastewater: A Liability or an Asset? by Robert C. Thomas, President Innovative Consultants, Inc. Newport Beach, California

The following article discusses how since early 1973, a Santa Barbara, California, laundry facility has been recycling wastewater through its water recla- mation process and producing water of high enough quality for reuse in the laundry operation. The princi- pal elements of the wastewater process are: 1) screening, 2) flow equalization, 3) mixing and chemi- cal treatment, 4) solids removal (dissolved air flota- tion), 5) second stage equalization, 6) filtration and polishing, and 7) treated water storage prior to re. heating and return to the laundry process.

If someone were to undertake an impartial poll of indus- trial executives and management asking the question, “Is industrial wastewater an asset or a liabililty?” almost without exception all would quickly respond, “A Liability.’’

It is surprising what can be accomplished by simply changing a point of view or rotating a familiar problem and looking at it from a slightly different direction. The Mission Linen Supply organization of Santa Barbara, California operates plants throughout the Western United States. Because of its numerous locations, ex- ceeding 35 at last count, the Mission Linen Supply man- agement recognized the necessity of dealing with the water pollution problem head-on.

Commercial linen supply and industrial laundries are major contributes to sanitary sewers and municipal wastewater treatment facilities. Approximately five per cent of all wastewater discharged to municipal sewage collection, wastewater treatment and disposal facilities comes from this segment of industry. The laundry wastewater is generally stronger than domestic sewage, often having a pH in excess of nine. Suspen- ded solids range from two to five times higher, and BOD5 is equal to or as much as four times higher than domestic wastewater.

It is difficult to typify the wastewater from a laundry facility. Constituents in the wastewater depend a great deal on the type of customers serviced by the linen sup- ply or industrial laundry facilities. In addition to the high level of suspended solids, one constituent particu- larly troublesome to local municipalities is the high level of oil and grease discharged in wastewaters from laundries. The oil and grease will range from 250

J Industrial Wastes120

milligrams per liter (mgll) on the low side, up to over 3,000 mgll for an industrial laundry doing a large per- centage of shop towels.

In early 1971, Mission Linen Supply began evaluation of alternative methods of treating and handling their wastewater. The research and development work in this new and somewhat unique area was tailored to meet the specific needs of the type of laundry facilities oper- ated by the organization.

As the research and development effort progressed through 1971 and into 1972, a new perspective or point of view was emerging. It was clear that a substantial amount of the value or money invested to purchase, condition, heat and otherwise treat the local water sup- ply remained after the water had been used only one time. By mid-1972, the standard perspective of looking upon wastewater as a liability changed. After Mission Linen Supply had purchased water from the City of San- ta Barbara, softened the water, conditioned it and heated it to the requisite temperature, an investment of approximately $1.44 to $1.56 per 1,000 gal had been made. This amount also included the cost of discharg- ing the wastewater to the City of Santa Barbara. A thorough evaluation of the various cost components of water supply conditioning was undertaken. Surprising- ly, a value equal to approximately 90 per cent of the money invested in the water remained after the water had been used only once.

A much clearer definition of the real problem was emerging. Perhaps the wastewater was not a liability, and it could be looked upon as an asset. The used water had a residual value of from $1.40 to $1.45 per 1,000 gallons. Unfortunately, the water was not usable in the condition it was being discharged to the sanitary sewer. Could the wastewater be treated or conditioned to a usable state for a cost less than the residual value of the water? Additional testing and evaluations were undertaken, and a prototype was developed for a waste- water treatment and water reclamation facility at the corporate headquarters in Santa Barbara.

The Santa Barbara laundry processes between 25,000 and 35,000 Ib of linens, uniforms and other textiles per day. Discharges to the city were running between 100,000 and 120,000 gal per day (gpd). The prototype water reclamation facility was designed to process

July/ August, 1975

' Rather than overflow rinse stages 2 and 4 into the 1,000-gal tank, Rinse Stage 4 overflows into rinse Stage 2 at a rate of five gpm. Stage 4, in effect, serves for make-up water to Stage 2, along with fresh water make- up. Stage 4 rinse water has a neutralizing effect on Stage 2, preventing a rapid buildup of alkalinity. The concept also tends to conserve water, as otherwise the fresh water make-up to Stage 2 would have to be at a higher rate. Rinse water from Stage 2, overflowed at ten gpm, serves as the second input to the 1,000-gal hold- ing treatment tank.

Solution from cleaner Stage 1 is drawn off at 18 gph into the large holding tank, serving as its third input. At this rate Stage 1 turns over every four weeks. A Lineguard@ 4100 controller manufactured by Amchem Products, Inc., automatically replenishes and main- tains the concentration of the cleaner within the pre- scribed parameters. This provides additions of replen- ishing cleaner in frequent, small increments, prevent- ing overflow of bath solutions unnecessarily rich in cleaner concentrations.

The mixture of chromic slurry, rinse waters, and cleaner in the large holding tank, as simulated after treatment has the following analysis:

Characteristics

Conductivity 25 micromhoslcm --- Chromium (Cr + 61, 'mgll Less than 0.05 --- Total chromium (Cr), 'mgll Less than 1 .O 6.0or less Zinc(Zn), 'mgll Less than 1 .O 6.0or less lron(Fe), 'mgll LessthanO.26 17.Oorless Nickel(Ni), 'mgll 0.3 6.0 or less

Suspended solids, mgll 745 445 or less Dissolved solids, mg I I 574 3,000or less

Analyses on supernatant or filtrate

Requirements of Treated Effluent By-Law No. 5933

PH 9.1 5.5-9.5

--- Total phosphate(POq), 'mgll 20 Total solids, mgll 1,319 ---

The treatment meets local regulations except for suspended solids. Suspended solids amount to 745 mg l l (6.2 Ib dry solids per 1,000 U.S. gal) containing hydrous oxides of chromium, zinc, and iron as well as calcium phosphate. The solids removal per shift would beabaout30Ibof dry solids, or150 Ib of solidscontain- ing 80 percent moisture for 4,800 gal of effluent.

A plate-and-frame filter press (Figure 2) capable of re- moving 155 Ib every three shifts from a solution rate of ten gpm, processes the final discharge stream to the sewer. The effluent passing through the plate and frame filter is free of hexavalent chromium and sus- pended solids, and has an acceptable pH. Drains on all tanks in the pretreatment system are installed so that no stage can be discarded without the solution first passing through the effluent treatment system.

An electronic bath level controller on the holding tank activates the filter feed pump when the solution mix is between two level probes. Also, a pH electrode is inserted into the holding tank. If the pH of the tank as measured by this probe is not the proper value to pro- duce suspended solids (8.5 to 9), the feed pump to the plate-and-frame filter cannot operate. This pH signal is also displayed on a nearby control board and recorded 0n.a tape as documentation for government authorities, should they want to look at past waste treatment per- formance.

Suspended solids generated in Stage 3, the zinc

July I August, 1975

phosphate conversion coating stage, are removed by a continuous filtration device known as a Gravi-T-Pak fi l - ter. (Figure 3) Bath solution is alternately pumped from the bottom of the tank's twin-cones to a reservoir at the top of the filter. The solution flows downward by gravity through four nylon sleeves where the sludge is filtered and collected, allowing the clean filtrate to return to the tank. The filter is emptied periodically by opening the bottom valve, letting the sludge drop into a drum for solid waste disposal. The final element of the waste treatment system, the grease trap for the cleaner stage, is skimmed off manually each day.

Prior to its installation, the Ministry of Environment expressed satisfaction with the sophistication of the proposed system. To quote from a letter to Simplicity from the Regional Engineer of the Industrial Waste Branch:

The treatment system proposed, pH control and filtration, represents the best available technology for the treatment of heavy metals, and it is our opinion that the system will meet the cur- rent requirements as well as any more stringent requirements in the forseeable future.

The cost of the waste treatment control system was $30,000, including design, hardware, and installation. Simplicity estimates operating costs at about $35 a week for material, while labor to operate is considered negligible. The Gravi-T-Pak continuous desludging filter produces additional operating savings of $2,000 a year by eliminating weekly manual maintenance of the con- version coating bath. I

Industrial WastesI19

$

90,000 gal in a ninehr operating period (approximately 10,OOO per hour, or a ate of 0.25 mgd). Normal operation of a laundry facility \nvoIves one eight-hour shift with appropriate lunch braaks and some extended operation beyond the first shift. During peak summer operation, the wash room portion of the laundry is extended for one-half shift. This, of course, increases the discharge to the city or local municipality.

A graphic description of the wastewater recycling process is presented in Figure 1. The figure is a sche- matic water use diagram rotating counterclockwise and indicating at the upper right-hand corner, the source of water and energy or raw resources being added to the water conditioning process at (the top of the cycle. From there the water proceeds to the laundry process, and is divided into two streams: 1) process losses, and 2) process wastewater. The process wastewater pro- ceeds to the wastewater treatment and water reclama- tlon facility. Downstream the treated wastewater is fur- ther divided into two streams: l) disposable solids and wastewater discharged to the local sewers, apd 2) re- claimed water that is routed to the reclaimed water re- conditioning facility. In the reconditioning step, the re- claimed water is heated to approximately 170 degrees F and stored in insulated tanks for reuse in the laundry on a demand basis. All reclaimed water bypasses the ini- tial fresh water conditioning process. When the re- claimed water is returned to the laundry process, the cycle is completed.

The wastewater is cycled through the process an average of two times prior to discharge to the sewer. The recycling reduces the wastewater discharged to the city by approximately 60 to 70 per cent.

The prototype was initially set up to take a segre- gated waste (the cleaner rinses from the laundry oper- ation). Satisfactory procedures for this mode of opera- tion were easily established. After the initial success, the process was modified to treat all wastewaters with-

out segregation. Piping changes were undertaken, and all wastewater needed to satisfy the demand for reclaimed water was removed from the wastewater sump on a non-segregated basis. Modifications to the chemical feed portion of the chemical-physical process were made to assure a satisfactory removal of solids, greases and oils and other detrimental constituents. Af- ter adjustment of the process, the water reclamation facility could satisfactorily treat non-segregated waste- water and produce water of high enough quality for reuse in the laundry operation.

After approximately three to five months of testing in early 1973, the water reclamation process was integrat- ed into the standard operation of the Santa Barbara laundry facilities. Since that time, the water reclamation process has operated every day for the past two years. Over 30 millionlgal of wastewater have been recycled through the process. The current demand for new or non-reclaimed water in the Mission Linen Supply - San- ta Barbara Facility is approximately one-third of the product contact water requirement. The current dis- charge of wastewater to the city is below 40,000 gpd.

The principal elements of the wastewater process are 1) screening, 2) flow equalization, 3) mixing and chemical treatment, 4) solids removal (dissolved air flo- tation), 5) second state equalization, 6) filtration and polishing, and 7) treated water storage prior to reheat- ing and return to the laundry process. In early testing, all of the conventional water treatment chemicals were investigated and rejected for economic reasons, sludge production or addition of dissolved constituents detri- mental to the laundry operation. After exhaustive test- ing, a group of polyelectrolytes were found to perform a satisfactory flocculation and solids removal function. Since the initial work, the polyelectrolytes have been modified to achieve even better results at dosages below 50 mgll.

(Continued on next page)

FRESH CITY WATER SUPPLY 25% TO 40% OF WATER DEMAND

5% TO

Figure 1

LAUNDRY

PROCESS

RECLAIMED WATER

RECONDITION I NG

WASTEWATER TREATMENT

AND WATER RECLAMATION I I L I WASTEWATER DISPOS U33t3

TO LOCAL SEWER SCH E M AT1 C 20% TO 30%

WATER USE DIAGRAM (OF WATER DEMAND)

LAL

Industrial Wastes121 - JulylAugust, 1975

Industrial Wastewater (Continued from preceding page)

The low chemical dosage rate results in minimum sludge production. Sludge production is in the range of 12 to 18 cubic feet per day. The sludge is removed at ap- proximately 9 to 12 per cent solids and further concen- trated to 18 to 22 per cent solids. The concentrated sludge is stored prior-to removal to a local solid waste sanitary land fill. During storage, some additional dry- ing and drainage is accomplished. When the sludge is removed to the land fill, the sludge is approximately 24 percent solids. It Is possible to press water from the sludge; however, there is generally no free water drain- age. The sludge is mixed with other solid waste from the laundry operation and represents only a small por- tion of the refuse removed from the facility. The sludge handling cost represents only a small percentage of the total operating cost and has been included in the over- all cost which will be covered in subsequent discus- sions.

The water reuse process, in addition to providing

industrial Wastes I22

water of a quality suitable for r use in the laundry, proves to be an effective pretreat ent facility. The flow through the process can be mo ified to direct all or only a portion of the excess wa i ewater through the process. The excess wastewater‘ can be treated to a level that meets or exceeds the local sewering agency requirements. If there are economic benefits to be de- rived, the excess wastewater can be routed through the entire process and discharged to the municipality prior to reheating.

Where pretreatment is an additional objective of a water reuse facility, process modifications can be in- corporated to remove a particular constituent to a specified level. Testing has been conducted on particu- lar constituents that are considered “non-compatible” and are frequently found in municipal waste ordi- nances. The effectiveness of the process to remove these constituents is very good; however, each pre- treatment objective should be studied individually and where economics are a principal concern, generally all potentially objectionable constituents cannot be removed with a single approach. On a mass emission basis, the process will satisfactorily produce effluent meeting any of the pretreatment requirements investi- gated by Water Reclamation Services (WRS) an affilia- ted organization that markets the Mission Linen Supply process. WRS has investigated potential installations in over half of the 50 states as well as in foreign coun- tries.

Some removal and treatability levels for the process are shown in Table 1. The reader is cautioned that generalization of these data carries some risk. In some instances, per cent removals can be maintained or im- proved i f the wastewater has much higher concentra- tions of the particular constituent, while at lower con- centrations, the percentage removal may be much lower while maintaining treatability level. Further, i f a particular constituent is a problem, usually it can be removed through modification of the chemical treat- ment andlor process flow or by adding other treatment equipment.

The water treatment and wastewater reclamation facility had an initial installation cost of between $60,000 and $65,000. This cost should be adjusted downward to approximately $42,000 because of extraor- dinary and unusual costs associated with development of the prototype. Unfortunately, due to the inflationary trend since the installation of the equipment, the cur- rent replacement cost is pegged at approximately $65,000.

It can be seen from the photographs of the water re- clamation plant (Figure 2) that some economies were achieved in the installation of the non-essential parts of the waste treatment facility. Since space was available, 10,000 gal surplus railroad tank cars were used as equalization and storage facilities for the reclaimed water. After installation and piping, the equalization tanks were insulated to minimize heat losses.

Flexibility is one of the major advantages of the pro- cess. The process is designed so that wastewater can be discharged from a numberof points throughout the treatment process. It is not necessary to treat all the wastewater to a complete or finished level. The point selected for discharge can be based on the require- ments of the local surcharge ordinances. Therefore, the combined stages of the water reclamation process can

JuiylAugust, 1975

be sized to treat only that portion of the wastewater needed for water reuse and to bleed off the portion of the wastewater that annot be used. The bleed off point selected is the one that can most economically meet the local municipal requirements for wastewater dis- charge. Two things are accomplished from this mode of operation. First, an alternative source of water has been developed for the water demand of the laundry room. Second, the majority of the water is recycled, substan- tially reducing the wastewater volume handled by the local municipality. This also has a marked impact on re- ducing the absolute quantity of pollutants being dis- charged from the laundry operation, and the water dis- charged to the city meets the local municipality’s re- quirements.

Wastewater discharged to the city had a substantial residual value. For the businessman, the ever-present question of profitability and return on invested capital must be fairly and honestly evaluated. In the case of the Santa Barbara installation, the economics were encour- aging. The cost factors involved operations and mainte- nance, equipment replacement, power and water treat- ment chemicals. The benefits to be derived from the water reclamation were savings on purchased water, sanitary sewer surcharges for disposal of wastewater, heating the fresh water supply, softening the water, and a reduction in laundry room supplies due to the high alkalinity of the reclaimed water. With all of the costs and benefits identified, it is possible to arrive at a bene- fit-cost ratio for the prototype facility.

In Table 2, the unit costs and benefits are expressed in centsllOO0 gal of reclaimed water processed. An ex- tension of the unit costs and benefits for a typical year’s operation is also shown.

The benefits or savings exceed the cost by over $14,000 per year. Of course, during the first three to four years of operation, the savings are only paper savings that defray the investment for the construction of the water reuse facility. After that time, the benefits are real savings, reducing the overall operational cost of the laundry. A review of the benefits will show that the savings are generally in areas that are sensitive to cost escalations resulting from changes in local ordinances, increased operating costs, higher energy costs, sup- plies and materials. While the operating costs of the water reclamation facility are susceptible to change, in- creases are not likely to occur as rapidly as in the area of the savings. Therefore, the savings derived from in- stallation of a water reclamation facility tend to in- crease in time. ‘

Considering the wastewater as an asset rather than as a liability has been profitable to the Mission organi- zation. What has been accomplished in Santa Barbara serves as an excellent example of what can be done by industries who take a fresh approach to water pollution con t rot.

If the story stopped at this point, most everyone would recognize the value of what has been accom- plished. However, only the primary benefits have been discussed, and those are limited to the items that can easily be seen. If we look further, we will find tremen- dous secondary benefits. These benefits accrue direct- ly to the City of Santa Barbara and the local taxpayer.

The city, like most municipalities throughout the United States, is currently in the process of planning the design and construction of a new wastewater treat-

ment facility. In Santa Barbara, this involves an ocean outfall conveying the treated water to a satisfactory dis- posal point offshore. The new facility, which is essen- tially a replacement of the existing plant, will include a new primary-secondary sewage treatment plant. The plant and outfall have the capacity of 11 MGD and an estimated project cost of $30 million ($2.73 million per MGD capacity). The capital expenditure by the City of Santa Barbara for a treatment capacity equal to the water reclaimed by the laundry is between $170,000 and $190,000. That capacity is no longer required because the laundry developed a water reclamation process. This substantial secondary benefit accrues to the city.

The water reuse facilities at the Mission Linen Sup- ply will reclaim 60 acre feet per year, thus reducing the current water demand. In order to determine the impact of a 60 acre ftlyr reduction, the present value of the future sumlemental water SUDD~V facilities must be

Figure 2 Suspended solids, oil and grease and other objection- able constituents are removed from laundry wastewater in an air flotation solids separation unit. studied. A recent estimate of the present value of a sup- plemental water supply of 60 acre ftlyr is in the range of $135,000 to $315,000.

Therefore, i f we take the combined secondary bene- fits accruing to the City of Santa Barbara, the total is between $305,000 and $505,000, or approximately 7 to 12 times the actual cost of the installation. It is not sur- prising that the city would like to see others follow Mission Linen Supply’s example.

JulylAugust, 1975 Industrial Wastes I23

Problems of Waste Disposal in the Arctic Environment

by Thomas G. Watmore Producing Department imperial Oil Limited Edmonton, Alberta, Canada

Since the presentation of this paper at the 26th Purdue In- dustrial Waste Conference, West Lafayette, Indiana, a num- ber of changes in respect to waste disposal have taken place In the Canadian Arctic. In November, 1971, the Government of Canada enacted the Territorial Land Use Regulations that require permits for virtually all industrial operations that are conducted on territorial lands. Each permit details the operating conditions in order to maximize environmental protection that takes into account the type and logistics of the operation and the seasons of the year, through to final surface restoration.

Fuel fired garbage incinerators are compulsory on all larger industry projects, and smaller work forces are re- quired to haul garbage to an incinerator site for burning and disposal. The 45-gallon drum is becoming relatively scarce in many areas. Tank farms, using welded steel tanks, have become new Arctic landmarks in many places. Where air- craft are theoniy means of transport, fuel bladders still must be used, however.

Within this time period, drilling for hydrocarbons has also moved onto manmade islands in the shallow waters of the Beaufort Sea, part of the Arctic Ocean. On these compact is- lands, water treatment units are used, and portable sewage treatment plants of the activated sludge process or rotating blological contactors have become part of the 6amp complex.

Becauselandfill in permafrost is difficult and recycling at present is too costly due to transportation, central sites are shortly to be proposed, by both government and induqtry, forthecollection of noncombustible metallic waste. Perma- nent production facilities, including waste disposal meth- ods unique to the Arctic, are now being built in Alaska, and lhdicatlonsarethat the Canadian Arctic will soon be into its design and production phase.

Extreme temperatures and sparse, scattered population in the Canadian Arctic make its waste disposal and pollution problems unique. Several methods have been used to deal with these problems while also protecting the environment.

Various waste disposal problems are present in the western Canadian Arctic, and more particularly, at points along the Mackenzie River and its delta area on the Arctic Ocean. The political boundaries of the Yukon and Northwest Territories contain all of the Canadian Arctic. This area of 1’12 million square miles, 53,000 of which is fresh water, contains a total population of some 50,000 people, chiefly inhabiting the southern latitudes.

Why then, do we speak of waste problems in such an enormous, sparsely-populated land? Many answers can be found. Ecologists and conservationists describe the north as one of the world’s last true wilderness areas. Governments, already facing difficult pollution prob- lems, have begun strong protective legislation to ensure protection of all theenvironment for the future. Industry realizes more than ever that environmental protection must be built into its operational planning, while the arctic environment itself, with its cold climate and permafrost, causes decay to be slow. This is beneficial

Industrial Wastes/ 24 /

in many ways but not where wastes are concerned.

“Permafrost, or perennially frozen ground, in many ways is defined exclusively on the basis of tempera- tureand refers to the thermal condition of earth mate- rials, such as soil and rock, when their temperature remains below 32 degrees F continuously for a num- ber of years. Permafrost includes ground that freezes in one winter, remains frozen through the following summer and into the next winter. This is the minimum limit for the duration of permafrost; it may be only a few inches thick. At the other end of the scale, permafrost may be thousands of years old and hundreds of feet thick. The mode of formation of such old and thick permafrost is identical to that of permafrost only recently developed.

Even asmall negative heat imbalance each year re- sults in the annual addition of a thin layer to the permafrost. This annually repeated process can produce a layer of permafrost hundreds of feet thick after several thousands of years. This process does not cause the permafrost to increase in thickness in- definitely but a quasi-eq ui I i brium is reached whereby the downward penetration of frozen ground is balanced by the flow of heat from the unfrozen ground below. Permafrost is not “permanently” frozen. Changes in climate and terrain can cause the permafrost to thaw and to disappear.”

The engineer, when designing services for the Arctic, must deal with many unique landforms that are a part and product of a cold climate and generally are high in ice content. Massive Ice Massive segregated ice exists along the Arctic coastline. Ocean storms began eroding a knoll underlain by massive ice, and summer than has con- tinued an active retreat of the ice. Measured between ’

1954 and 1970, the ice had thawed back 200 feet. The overburden is about 15 ft thick, and within this, two ice wedges can be seen extending downward and into the massive ice. About two ft of soil and vegetation cover the ice wedges, and this indicates the depth of ground thaw in thesummerseason, orwhat is termed theactive layer. A fresh slump, or thermokarst, occurred naturally in the Eskimo Lakes, northwest of Tuktoyaktuk in July, 1970. Evidence of a former and larger slide seems to be indicated by thecontourand vegetation behind the 1970 feature. One can readily visualize what would happen to sewer lines, heated or cold oil lines, or even a structure on pilings located in this vicinity. What also of the pollu- tion problem?

Massive ice is very extensiveand very difficult to pre- dict throughout permafrost areas. One occurrence has

JulylAugust, 1975 (Continued on page 27)