Drinking Water&

Wastewater

Regulation and Treatment

Drinking Water Regulations• 1893 - Interstate Quarantine Act

– Result: Prohibition of Common Drinking Cup on Interstate Carriers – created a market for Dixie® cups

• 1914 - Microbiological Standard– 2 coliforms / 100 ml

• 1925 - New Microbiological Standard– 1 coliform / 100 ml

• 1942 - Maximum Concentrations for Constituents:Lead Fluoride ArsenicSelenium Barium Hexavalent ChromiumCopper Magnesium Iron + ManganeseZinc Chloride SulfatePhenolics* Total Solids Alkalinity

*Phenol = carbolic acid, addition of methyl group forms cresols, o, m, or p

Drinking Water Regulations1962 Limits for:

Alkyl benzene sulfonates (synthetic detergents)

Carbon-chloroform extract (organic residues)[Adsorption on activated carbon, chloroform extraction, gravity

quantification]

Barium Cadmium Cyanide

Nitrate Silver Radioactivity

Safe Drinking Water Act of 1974Enacted over concern about organic materials in drinking water

Established Maximum Contaminant Levels (MCLs) for several substances [Enforceable]

Federal Guidelines - Secondary MCLs (SMCLs), [Nonenforceable]

1975 - National Interim Primary Drinking Water Regulations

Amended repeatedly, now include:• Microbiological Contaminants

– Total and Fecal coliforms, E. coli, Turbidity

• Radioactive Contaminants– Beta/photon emitters, Alpha emitters, Combined radium

• Inorganic Contaminants– 15 elements or materials

• Synthetic Organic Contaminants including Pesticides and Herbicides; Volatile Organics– 54 compounds and groups of compounds

Drinking Water Treatment

S A M P LIN GP R O G R A M

D IS IN FE C T IO N

FLU O R ID A T IO N

G R O U N D W A TE RS O U R C E S

SURFACE W ATERS O U R C E S

C LE A ND R IN K IN G W A TE R

DELIVERED TO CUSTOMERS

Groundwater Treatment Options

A Q U IFE R

A Q U IFE R

AQUIFER

AERATION

IRON & MANAG NESER E M O V A L

A Q U IFE R

S O FTE N IN G

FILT R A T IO N

W A T E R TOS YS TE M

Surface Water Treatment Options

W A T E RS O U R C E

W A T E RS O U R C E

FILT R A T IO N

W A T E RSOURCE

IN T A K ES YSTEM

COAGULATION &FLO C C U LA T IO N

F ILT R A T IO N

W A T E R TOS YS TE M

Drinking Water Treatment Units or Processes

• INTAKES• AERATION• COAGULATION & FLOCCULATION• CLARIFICATION• FILTRATION • DISINFECTION• SOFTENING• TASTE & ODOR CONTROL• IRON & MANGANESE REMOVAL• TRACE METALS & ORGANICS

AERATION(Usually for Groundwater)

• ADDS OXYGEN

• REMOVES:– Carbon Dioxide Hydrogen Sulfide– Methane Taste & Odors

• REMOVAL MAY BE BY:– Oxidation Volatilization

• Iron & Manganese Organics

Coagulation, Flocculation & Clarification

Coagulation changes the electrical charge of suspended particles and colloids; allows attachment to each other. Coagulants are usually cations: Alum, Ferric Sulfate, Lime (CaO)

Chemical/Physical process of mixing special purpose chemical from flow and removing the resulting product

– Silts/Clays, Viruses, Bacteria

– Fulvic & Humic Acids, Minerals, Organic Particulates

Flocculation is the agglomeration of particles into settleable particles

Clarification - sedimentation of floc particles, allows longer filter runs, settling velocity of the floc allows particle removal before the water leaves the basin

Drinking Water Filtration

• Rapid Sand Filters are most commonly used for surface water

• May be gravity or pressure flow– Some States prohibit pressure flow

• Fine-to-course (back wash result)• Course-to-fine (multi-media)

– Anthracite, Sand, Course Garnet, Fine Garnet• Rapid Sand filters may clean 1 - 2 gpm/ft2

• Alternatives include: microscreens, diatomaceous earth filters, cartridge filters

DISINFECTION• CT concept is the current basis for disinfection theory:

CT = K

C = disinfectant concentration

T= contact time

K= proportionality constant, variable with different organisms

Ohio regulation = 30 min contact time, 0.2 mg/l Cl2 residual

• Chlorination is most common in the U.S.

– Effective, low cost, proven technology

– Reactions with natural aquatic organics produce trihalomethanes -- suspected carcinogens

• Ozonation is popular in France, Germany, Canada, and Russia

• Chlorine Dioxide gaining acceptance in Europe and U.S.

Chlorine Chemistry

Cl2 + H2O -----> H+ + Cl- + HOCl

HOCl = Hypochlorous Acid, is the most active ingredient, concentration is pH dependent; dissociates to:

H+ + -OCl

Active against (listed in decreasing order):

Bacteria Viruses Protozoans (cysts)

Chlorine reacts with Ammonia (NH3) to produce mono, di, and trichloroamines

NH2Cl NHCl2 NCl3

Chlorine Residuals & Chlorine Demand• Free Chlorine: Cl2, HOCl, -OCl• Combined Chlorine: Chloramines• Free Chlorine has strong disinfecting powers but is

quickly dissipated• Combined Chlorine is slower acting but remains in

solution longer and provides longer-term protection• Chlorine Demand = the difference between the amount

of chlorine applied and the amount of free, combined, or total chlorine remaining at the end of the contact period

• Anything oxidizable can produce a chlorine demand, including pathogens, organics, particulates, sulfides, ammonia, etc.

Alternative Disinfectants

Ozone – O3, powerful oxidant, alternative to chlorine– Effective at low doses– Expensive (capital and operating costs)– Produces no residual

Chlorine Dioxide– ClO2, an unstable gas, produced at the point of

use from sodium chlorite, NaClO2 – Nearly as effective as chlorine, does not react

with ammonia to produce chloramines, or with other organics to form trihalomethanes

BIOFILMS• In many environments, microorganisms form,

and exist in, complex, protective layers called biofilms

• Biofilms may form in any part of a drinking water distribution system. Cooling towers can support robust biofilms.

• Disinfectants may be unable to attack or completely remove the organisms in biofilms

• Most biofilms are made up of non-pathogenic organisms; however, pathogens may be protected in such an environment

SofteningReduction in dissolved calcium and magnesium reduces

deposits in distribution system - scale formation (CaCO3)

Hard water reacts with soap to form films that are difficult to remove

Hard water deposits form scale in boilers

Softening also removes some trace inorganics – Pb, Cd, Ag, Ba, Cr, As, Hg, and RaLime-soda process adds quick lime (CaO) or hydrated lime

[Ca(OH)2], precipitating calcium carbonate (CaCO3)

Ion-exchange removes Ca2+ and Mg2+ and replaces them with Na ions; often used in homes

Taste & Odor Control

• Very low concentrations of metals, salts, or organics may produce detectable levels in sensitive people - iron, copper, manganese, and zinc, magnesium chloride and bicarbonate, chlorinated organics; fungal and algal metabolites; hydrogen sulfide, other sulfur compounds

• Activated carbon is often very effective in removing organics

• Oxidation (chlorine, chlorine dioxide, ozone)

Iron & Manganese Removal Iron and manganese cause staining and leave noticeable

residuals at very low concentrations

Fe >0.2 mg/l Mn >0.1 mg/l

Iron promotes growth of “iron bacteria” in mains that increase friction and power consumption

Oxidation produces less soluble compounds and precipitation is often used for removal

Trace MetalsIron, Cadmium, Lead, Copper, Zinc may come from the

plumbing system; others may be from the aquifer

Corrosion control processes may be the most effective means of reducing these concentrations - precipitation of a layer of calcium carbonate often provides a nonreactive surface

Turbidity A measure of suspended particulates in water - clays,

microorganisms, organicsHighly turbid waters are difficult to disinfect because of high

demands - large amounts of materials to be oxidized; organisms protected from exposure to disinfectants

Coagulation and flocculation, and filtration are common removal methods

Trace OrganicsSolvents, hydrocarbons, etc. may come from the aquiferModified organics may be the result of disinfection processesHumic and fulvic acids are poorly defined and are common in

natural watersTOC and TOX are broad tests of water qualityPrecipitation, filtration, adsorption, and oxidation may all

remove some of the materials

Fluoridation

• The fluoridation process was very controversial when initially implemented

• Low concentrations (1 - 2 mg/l) of fluoride provide strong protection against tooth decay

• Slightly higher concentrations (> 4 mg/l) can cause discoloring of teeth

CROSS CONNECTIONS– Accidental contamination of drinking water can

occur during routine plumbing modification, sewer backups, floods, earthquakes, careless homeowners, etc.

FOAMING AGENTS– Surfactants (the active part of detergents) can

get into surface water through incomplete sewage treatment

– Groundwater sources include septic tank systems

Nitrate & Nitrite

• Nitrate is common in natural waters at 1 to 2 mg/l

• Nitrate (NO3) is reduced to nitrite (NO2) in the digestive system - reduction is more complete in infants than adults - because of more alkaline conditions in system

• Excess nitrite produces methemoglobinemia in infants by oxidizing hemoglobin to methemoglobin which cannot carry oxygen

• Nitrosamines formation (suspected carcinogens) can also occur from nitrate or nitrite

• TOTAL DISSOLVED SOLIDS– High TDS may increase corrosivity because of

increase conductance– High sodium may be of health concern

• CORROSIVITY– Decreases life of plumbing system– Solubilized metals, perhaps in toxic quantities - lead

and cadmium are of most concern– Copper, iron, and zinc produce tastes and stains– Corrosion can shield microorganisms from

disinfection processes– Water may be characterized as passive or aggressive

CLEAN WATER ACT - Background• Rivers and Harbors Act of 1899

– Prohibited discharge of refuse without a permit from the Secretary of the Army

• Water Pollution Control Act of 1948– Gave primary responsibilities to the States

– Provided construction funds, Money never appropriated

• Water Pollution Control Act Amendments of 1956– Authorized Grants for construction

– Provided funds for research into Health Effects

• Other minor Acts in 1961, 1965, 1966, 1970

• Federal Water Pollution Control Act - 1972 - PL 92-500– Goal of “fishable/swimmable” water

– Construction Grants for Sewage Treatment Facilities

• BPT - Best Practicable Treatment

• BAT - Best Available Treatment

– Concentrated on Oxygen Demand, Suspended Solids

– 1976 - NRDC v. Train - Consent Decree - resulted in...

• Clean Water Act - 1977 - PL 95-217 • Wetlands Resources Act - 1986• Water Quality Act Amendments of 1987

– Required EPA regulations on storm water runoff

– Required State nonpoint source management programs

TITLE I -RESEARCH AND RELATED PROGRAMS

• Sec. 101 - Declaration of Goals and Policy -- Objective: Restore and maintain the chemical, physical, and biological integrity of the Nation's waters.

• Goals:1. Eliminate pollutant discharges into navigable

waters by 1985.

2. Interim goal to protect fish, shellfish, and wildlife and provide for recreation in and on the water by July 1, 1983.

3. Prohibit the discharge of toxic pollutants in toxic amounts.

TITLE III - STANDARDS AND ENFORCEMENT

• 304 - Information and Guidelines - provides for development of water quality criteria. Defines conventional pollutants - including, but not limited to, biological oxygen demand, suspended solids, fecal coliforms, and pH, --- specifically excluded thermal.

• 305 - Water Quality Inventory - requires States to provide a water quality description, an inventory of point-source dischargers, and an estimate of costs of improving quality.

• 306 - National Standards of Performance - requires a list of categories of sources and establishment of new source performance standards for those categories

TITLE IV: PERMITS AND LICENSES

Sec 402 - National Pollutant Discharge Elimination System - (NPDES) establishes requirements for issuing permits and State implementation of the program.– Excludes: Irrigation return flows, Storm water

runoff from Oil, Gas and Mining operations– Anti-Backsliding - renewed permits must be as

stringent as the original– Storm water is included by October 1, 1993

ADDITIONS, AMENDMENTS

• LIMITATIONS ON DISCHARGE OF RAW SEWAGE BY NEW YORK CITY– North River Plant - required to have advanced

preliminary treatment by Aug, 1986– Red Hook Plant - required advanced preliminary

treatment by Aug, 1987

• BOSTON HARBOR AND ADJACENT WATERS– Authorization for constructing waste treatment

works for providing secondary treatment

Oil Pollution Act

• Revised penalties for oil discharges– Administrative penalties of $125,000 for

violations of regulations or discharges– Civil penalties of $25,000/ day for discharges,

or $1,000/ barrel of oil– Gross negligence or misconduct minimum

penalty of $100,000

CONVENTIONAL POLLUTANTS

• Several are “Empirical,” derived by experimentation• Biological Oxygen Demand - test using microorganisms that

measures oxygen uptake over five days

• Suspended Solids - quantified by filtration of a sample and drying and weighing the filter

• Fecal Coliform Bacteria - microbial analysis dependent upon incubation conditions and selective media

• pH - measured directly

• Oil and Grease - derived by extraction of a water sample with a solvent and either an infra-red (IR) measure of the solvent, or a gravimetric measure of the residue

Pretreatment RegulationsIndustrial discharges into POTWs (40 CFR 403)

– POTWs with flows > 5 million gpd, or smaller POTWs with significant industrial discharges must establish local pretreatment programs

– National standards must be enforced– Hazardous wastes are the focus of regulation– Significant industrial users must meet reporting

requirements:• Users subject to categorical pretreatment standards

• Users of > 25,000 gpd of processed wastewater

• Users that make up >5% average organic capacity

• Other users with a reasonable potential to adversely effect the POTW’s operation

Wastewater Treatment

• Collection System– Sewage

• Domestic (sanitary)

• Industrial

• Mixed

– Stormwater• Separate Systems

• Combined Systems

• Infiltration (20 to 3,000 gal/acre/day)

Unit Operations & Unit Processes

• Unit Operations - Treatment methods using physical forces

• Screening Mixing Flocculation

• Sedimentation Flotation Filtration

• Aeration (gas transfer)

• Unit Processes - Treatment methods using chemical or biological reactions

• Precipitation Adsorption Disinfection

• Biodegradation Nutrient Removal

Treatment Levels

• Primary Treatment - (preliminary), physical unit operations – Removal of constituents that cause maintenance or

operational problems -- debris, grit, oil and grease,

• Secondary Treatment - chemical and biological unit processes – Removal of biodegradable organics and suspended solids

• Tertiary Treatment - (advanced), combinations of all three methods– Removal of residual nutrients, toxics, specific

contaminants

Typical Treatment ProcessBar Grit

Influent Screen Chamber Primary

Clarifier

Anaerobic Activated

Digester Sludge Unit(s)

Disinfection Secondary

Clarifier

Effluent

SludgeReturn

SludgeDisposal

Industrial WastewaterTreatment - Differences

• Equalization - hydraulic residence time at least equal to activated sludge unit, may be several times longer

• Oil Separation– Dissolved Air Flotation, Dissolved Gas Flotation

– Corrugated Plate Interceptors

• Sludges may be hazardous by regulation

Design Criteria

• Flow RatePeak Hour Maximum Day

Maximum Month Minimum Hour

Minimum Day Minimum Month

• Mass LoadingMaximum Day Sustained Peaks

Maximum Month Minimum Month

Minimum Day

WastewaterDaily Flow Pattern

Midnight Noon Midnight

Reactor Types• Homogeneous Reactions:

– Batch Reactor– Plug-Flow Reactor– Complete-Mix Reactor, Stirred Tank Reactor– Complete-Mix Reactors in Series -

• May be significantly more effective than the same volume in a single unit

– Arbitrary -Flow Reactor• Heterogeneous Reactions:

– Packed-Bed Reactor– Fluidized-Bed Reactor

Mass-Balance Analysis

Accumulation = Inflow - Outflow + Generation

V dC/dt = QCo - QC + V(-kC)V = volume of reactordC/dt = rate of change of reactant concentration within reactorQ = volumetric flow rate into/out of reactor

Co = reactant concentration in influentC = reactant concentration in reactor and effluentk = first-order reaction-rate constant

Mass Balance Applications• Model constituent biodegradation or removal

(volatilization, precipitation, etc.)• Model solids (sludge) formation

Common Operational and Design Practices

• Gravity flow through system– Only pump the water one time

• Parallel units – Allow operational flexibility and maintenance

• Minimize human contact with materials

SIMPLIFIED TREATMENT FLOWFairborn Plant

Raw

Sewage

Grit Tanks Oxidation

Ditches

Clarifiers

SludgeReturn

Disinfection

Effluent toMad River

DigestersLandfill

Fairborn NPDES Permit Requirements

• Sampling Stations– Plant Outfall– Waste Sludge– Raw Sewage Influent– Upstream at State Route 235– Downstream - 200 ft south of lift station at River

Mile 8.6

• Samples:– Composite samples of at least three grab samples

proportionate in volume to the sewage flow rate at the time of sampling...intervals of at least 30 min., but not more than 2 hours

FairbornPerformance Statistics

• Average Daily Flow (mgd) 3.795• Average Influent:

– Suspended Solids 198 mg/l– BOD 143 mg/l– Ammonia 16 mg/l

• Average Effluent:– Suspended Solids 6 mg/l 97%– BOD 3 mg/l 98%– Ammonia 0.1 mg/l 99%