Municipal Wastewater Treatment Facilities


Case 1.

The population increase in the state of Easy Living has brought about growing demands for the establishment of new cities in the state. The cities would be constructed on land owned by the state. The state would sell the land to the developers. However, it is the responsibility of the state to supply these new communities with water, energy, schools, and recreation areas. The state is also responsible for building municipal wastewater treatment facilities for these new cities. A typical city would have the potential for approximately 100,000 to 200,000 residents over the next 30 years. These new cities will also attract industries such as food processing, metal and light chemicals. Typical wastewater influent streams would resemble those of an urban city. Design a suitable wastewater treatment facility for one of these cities.

This project requires a teamwork solution.


Case 2.

Design a wastewater treatment facility that can handle 20 MGD. Sources of wastewater are commercial, household and pretreated industrial waste. The following table gives stream influent characteristics:

Component

Concentration (mg/l)

BOD18
Suspended Solids180
Biomass26
Debris70
Copper0.3
Lead0.1
Organic Compounds3.0
Oil and Grease1.0
Water999,600


The treatment process should involve among others; screening, sedimentation, clarification, thickening, digestions, and filtration. You can use your own unit operations and unit processes scheme or any wastewater treatment software such as SuperPro Designer. The effluent stream is discharged into a nearby river.


Case 3.

The population increase in the state of Easy Living has brought about growing demands for a new supply of potable water, especially in the area of Freedom City (a residential community). It is anticipated that the city will have a population potential for approximately 50,000 new residents over the next 50 years. 1,000 visitors per day are also epected when the new shopping mall is completed within the next two years. The existing treatment facilites are limited and allow no future expansion. The purpose of any treatment plant is to provide water that is chemically and bacteriologically safe for human consumption and domestic use. A surface water reservior is located 8 miles north of Freedom City and is assumed to contain enough water supply at all times. Preliminary studies by the Pussy Cat water company indicate that the average use of water per capita is 300 gallons per day. This includes residential interior, business, schools, recreation and fire fighting use. It also indicates a peaking factor equal to 2. The company also studied the quality of the reservior water. Analysis of a typical sample of the surface reservior water gave the following information:
  1. amount of dissolved oxygen = 5 mg/L
  2. turbidity = 8 NTU
  3. suspended solids = 30 mg/L
  4. BOD5 = 8 mg/L
  5. dissolved inroganic salts (mostly calcium) = 300 mg/L
  6. 2000 fecal coliform per 100 mL
  7. some debris and fish
  8. no radioactive contaminants
The city has designated a space located 4 miles south of the reservior as a site for the construction of a new water treatment plant. It has an elevation 400 ft lower than the reservior. This elevation is also 200 ft higher than the ground surface of the city.

Design a suitable water treatment plant that solves the water shortage problem and meets the EPA standards. The following design criteria apply:
  1. Minimum detention time in a sedimentation tank is 4 hours
  2. Maximum overflow rate in a sedimentation tank is 30 m3/m2 a day.
  3. Efficiency for sedimentation tank no less than 85%
  4. Filtrate rate in a treatment filter is 3 L/m2 per second
  5. Pumping station efficiency is no less than 80%
  6. Flocculation average detention time no less than 30 minutes
Justify and design parameters used and give references for any assumed values.


Pharmaceutical Wastewater Treatment Systems


Case 1.

Curepharma is engaged in the production of soft gelatin capsules (vitamins and dietary supplements). These products consist of gelatin shells and medicine or vitamin fill materials. In order to produce softgels, the gelatin and medicines or vitamins muse be processed.

The gelatin is melted down to a liquid, then cast into a sticky ribbin like form of specific dimensions. This ribbon is then lubricated with oil so it can be drawn through the mechanical components of the encapsulations machine without sticking to the machine parts. The fill material must be liquid and must have an edible oil base since a water base liquid would destroy the gelatin ribbon. Rotary dies cut capsule shapes fromthe ribbons while a pump simultaneously fills the capsule shell as it is being formed. This process consumes 20,000 pounds of processed gelatin per day and 3,000 gallons of food grade oil per day.

Because the products are manufactured for human consumption, the cleanlienss of equipment is very important. To remoive the oils and vitamin and medicine powders from tanks, trays, pumps, and other manufacturing equipment, manual and automatic washing processes utilize strong detergents which emulsify the oils and powders.

The wastewater resulting from the procesures discussed above is rich in oils and high in pH and heavy with sediments in the form of mineral and vitamin powders. While all the oils and soaps used are non-toxic and FDA approced, the company's wastewater permit requires and effluent which meets the EPA levels of oil and grease and acceptable pH values. Design a treatment system which can handle a 10,000 gallon per day of wastewater produced by Curepharma.


Case 2.

A wastewater system of a vitamin gel capsule manufacturing company collects waterwater from the following areas:
1 - Formulation
The pot wash sink
2 - Wash Room
a- Capsule Tray washing machine
b- Formulation Tank washing pit
c- Formulation Tank Wash Room sink
3 - Maintenance Shop
a- Parts washing sink
b- Pump washing pit
4 - Porter station
a- Mop Washing pit
The company uses food oils and non-toxic petroleum products to facilitate the encapsulation process. The wastewater resulting from the manufacturing process is high in oils and grease (5,000 - 15,000 ppm) and heavy sediments (mineral and vitamin powders). Its pH ranges from 9 to 12 and its BOD is between 2,000 and 5,000 mg/lit.

Design a treatment facility capable of producing an effluent that meets EPA standards and regulations. The company generates approximately 20,000 gallons wastewater per day.


Case 3.

The growth of the pharmaceutical industry has been steady over the past years. Their products are classified according to the SIC system as a) medicinal, chemical, and botanical products, b) pharmaceutical preparations, c) in vitro and invivo diagnostic substances, and d) biological products, except diagnostic substances (US EPA). The pharmaceutical industry utilizes batch type reactions to manufacture its products. Cleanliness is an important factor since the products are eventually consumed by humans. Typical pharmaceutical products include vitamin supplements, aspirin, saline solution, and shampoos.

Depending upon the specific product, the raw materials, processes employed, generated wastes for the industry vary. The industry can be divided into the followinf sections:
  1. research and development
  2. chemical synthesis
  3. natural product extraction
  4. fermentation
  5. formulation
The fifth segment will be analyzed, specifically a soft gel capsule production.

Soft Gel Capsule Production

The formulation process involves the production of gels, capsules, creams and ointments. In the production of soft gels, the capsules are prepared by melting gelatin into rotary die plates. To avoid sticking to the rotary plates and other mechanical components, oil is used to lubricate the equipment. A capsule is formed when the rotary plates are brought together combining the two halves of the capsule shell. Afterwards, the fill material, a non-aqueous solution, is injected into the empty shell capsules, thus producing a soft gelatin capsule. The finished product can be a vitamin supplement or an over the counter medicine.

Process Waste Description

The wastes generated by the soft gel capsules production results from the cleaning and sterilization of equipment, chemical spills, rejected products, and lubricants. The equipments must be thoroughly cleaned since the capsules are for human consumption. The oil and medicine powder residues from the machines are mechanically and heand cleaned. Strong detergents are utilized to emulsify the oils and powders. A typical waste stream composition includes oil, grease, and hydrocarbons. Therefore, the industrial pretreatment facility for soft gel capsule production must handle oils and sediments. In addition, the water is basic with a pH range os 9-12.

For a plant with the following Influent Stream Characteristics;

ComponentFlow Rate, kg/hrConcentration, gm/lit
Oil and Grease15093.8
Petroleum Hydrocarbons340212.5
TSS106.3
Water1100687.5


Design a treatment facility that will produce and effluent within the range of POTW's regulations. The treated effluent is ultimately discharged into sewers.



Electronics and Electrochemical Industrial Waste Treatment Facilities


Case 1.

The Printed Circuit Board: Electroplating

Since its development, printed circuit board has virtually replaced hand wiring as a means of connecting electronic circuitry in military and commercial applications. A printed circuit board consists of a circuit pattern placed on a nonconductive base. These patterns are made with conductive metals such as nickel, copper and aluminum. Depending on its use, the design and complexity of the printed circuit board varies.

The wastes generated in the production of printed circuit (PC) boards range from solid wastes such as failed PC boards to hazardous wastes such as nitric acids. The principal sources of wastes are; cleaning and surface preparation operations, catalst application and electrolyze plating operations, pattern printing and masking operations, electroplating and etching operations

The materials used for each operation dictate the characteristics of the wastewater resulting from such operation. It includes spent solvents, airborne particles, acids and metals.

In a typical electroplating process, the influent waste stream consists of the following:
ComponentFlow Rate (kg/hr)
copper14.5
nickel12.2
lead10.4
cyanide6.2
water500

Design a treatment facility capable of treating 4000 gallons per day of liquid waste. The effluent stream is to be discharged into a public sewer system. Common unit operations used in such treatment facilties might include among others; ion exchange, granular media filtration and neutralization.


Case 2.

Pollution Prevention or Reduction at the Source; Computer Impact Printers:

Printbands are parts of many compnenet parts used in the manufacturing of impact printers, Orintbands are stainless steel belts chemically machined via a photolithographic process in which stainless steel panels are treated with etching solution of ferric chloride and hydrochloric acid (IBM).
Fe + 2 FeCl3 = 3 FeCl2

The dissolved streel spent etchant (ferrous chloride) solution contains also chromium and traces of molybdenum. The treatment of the waste etch solution involves neutralization of the hydrochloric asid and precipitation of metals. The presence of chromium deposits in the sludge makes it hazardous and results in an expensive disposal cost.

Expansion of the computer industry in the last 15 years requires large investment in on-site sludge handling and off-site disposal treatment. To handle the voluminous waste etch solution alternative technologies which 1) ensure continuous supply of ferric chloride, 2) encourage conservation practices, and 3) reducewaste and minimuze treatment costs are needed.

Suggest, discuss and design at least two alternative strategies that will address this problem.


Case 3.

Treatment Plant from and Electrochemical Industry

Wastewater treatment system design requires two phases, (1) the identification of the chemical compounds in the waste, the sources of these compounds in the industrial process, the toxic effects of these chemicals, the concentration lvels of these chemicals and the technologies capable of reducing the concentrationss of these contaminants to an acceptable non-toxic levels, (2) the selecting, combining and arranging of the unit treatment operations and processes that will achieve the treatment objectives.

The design or simulation of a chemical plant or a wastewater treatment facility becomes more realistic with the use of actual site data. Whether it involves utilizing the quantitative aspects of the influent or effluent stream concentrations or basically just obtaining a listing of the chemicals used, the student has a better chance of practically solving or simulating the facility. In turn, the sizes of the unit operations and costs of the plant will not be ridiculously meaningless.

The wastes generated by an electrochemical industry have to be treated first before discharging it into the sewers. The main source of pollution comes from two general chemical categories: 1) heavy metals and 2) organics. The typical influent wastes' characteristics include chromium, copper, benzene, and toluene. The concentration values for these and other chemicals can be obtained from the electrochemical folder in the enviro.wb2 database. The effluent stream from this database readily meets the stringent EPA guidelines. Design a feasible, cost-effective treatment facility that can reduce the influent stream characteristics to the desired effluent stream values. Note that the flow rates are not given. Look for the typical flow rates used in this industry and state any assumptions made.



Battery Industries


Case 1.

The waste generated by battery industries contains chemicals that are not only toxic but also resistant to degradation. Thus, they represent serious health, safety and environmental problems. Manufacturing processes involve casting, chemical reactions, pasting and curing, container and tank formation of batteries, quality control work,... Waste that could result from such processes include among others; acids, alkalies, heavy metals,oil and greases, metallic dust, and spent and washing water.

reducing pollution at the source through new technologies or minimizing toxic waste is an objective of these industries. Companies are looking for ways to replace some of the raw materials used. They are also investigating more efficient methods that can recycle some of the compounds foudn in the waste.

Until new technologies are found, industry isrequired to treat its waste before discharging into sewers or downstream reserviors. For such an existing battery manufacturing company, design a treatment plant capable of treating 1000 gallons of liquid waste per day.


Case 2.

Pollution reduction and prevention in industry became an important objective and a priority for both the Environmental Protection Agency and the manufacturing companies.

Materials used in battery industries (lead, chromium, sinc, mercury, arsenic, camium) are high sources of toxicity. Battery-related pollution is found in raw materials, manufacturing processes, use and disposal.

The "Forever Working" Battery Company is under construction. The company is a small to medium organization. Preliminary and pilot plant studies indicate that the generated influent waste stream will be around 500 gallons per day and includes the following;


Parameters (mg/lit)

Chemical Oxygen Demand (COD)1200 - 1300
Total Suspended Solids60 - 70

_

Heavy Metals (mg/lit)

Copper1 - 1.5
Lead30 - 36
Nickel0.5 - 0.7
Silver0.01
Zinc3 - 5
Chromium1 - 1.2
Cadmuim0.1
Arsenic0.2 - 0.4

_

Other Substances (mg/lit)

Oil and Greases8 - 10
Cyanide0.04 - 0.06


You have been asked to lead a team responsible for assuring that the "Forever Working" Company meets and sustains the regulations of all federal and state environmental agencies. Develop a treatment plan that will accomplish this task.