Wastewater Engineering 1

Wastewater Treatment Facility

• General definition: treats wastewater generated from various sources (e.g., domestic water, human waste).
• Sanitary definition: derived from the Latin word "Sanita," meaning healthy.

Wastewater as a Resource

• Wastewater should be viewed as a resource for reuse and recharge.

Wastewater Sources

• Industrial: Requires reduction of carbon loading.
• Nitrogen and Phosphorus: Support algae growth.
• Office: Wastewater treatment is essential to protect Laguna Lake.

Wastewater Treatment Processes

• Physical Separation: Utilizes settling tanks.
• Microorganisms: Used when there is high organic content.
• Chemical Substances: Applied if the wastewater source is industrial.
• Treatment removes pathogens and reduces pollution.
• Manila Bay: Classified as Class SD, indicating low hazard.
• Contamination: Causes waste and poses a nuisance to public health; high hazard.

Regulatory Standards

• DAO 34, 35, 2016-08: Regulatory standards that must be adhered to in wastewater treatment.
• Goal: Convert nonpoint sources to point sources through end-of-pipe treatment.
• Examples: Commercial livestock and poultry farming.

Historical Context

• Nightmen: Refers to individuals who collected feces.
• Cholera Disease: Historical disease related to sanitation.
• Pioneer of Epidemiology: First created ancient GIS (Geographic Information System).
• Broad Street Outbreak (1854): Significant event in the history of epidemiology.

Wastewater Quality

• Purification: From large coarse gravel to peaty soil, using an aerobic type of treatment.
• Permit: Required to discharge water to water bodies.
• Fats, Oil, Grease (FOG): Chronically toxic and persist in the environment.
• Carbonaceous Biological Oxygen Demand: Important parameter for water quality.
• Administrative Order: Relevant to regulatory compliance.
• Saline: Indicates the poorest water quality.
• Fresh Water: Represents the highest quality for freshwater.
• Marine Water: Indicates the highest quality for marine water.

Water Source

• Source for Drinking Water: Requires disinfection.
• Pasig River: Intended to have coral reefs; no discharge of effluent allowed.
• Manila Bay: Regulations are based on Supreme Court decisions.

Wastewater Terminology

• Influent: Raw wastewater entering a treatment plant.
• Effluent: Treated water discharged from a wastewater treatment plant or from an industrial source.
• Strong Wastes: High organic content, with initial BOD equal to or greater than 3,000[mg/L].
• Appeal: Industries may appeal due to difficulties in meeting parameter standards.

Wastewater Sources and Types

• Domestic (sewage) wastewater
• Industrial wastewater
• Storm sewage
• Combined wastewater

Inflow

• Infiltration
• Direct inflow
• Total inflow
• Delayed inflow

Wastewater Types:

• Gray water: Consumed water in the kitchen, bathroom, and laundry.
• Black water: Water from flush toilet (feces and urine).
• Yellow water: Urine separated from toilet and urinals.
• Brown water: Black water without yellow water.

Wastewater Composition

Domestic Sources

• Originates from residential, commercial, institutional, and similar facilities.
• Stale sewage: Has odor of hydrogen sulfide, dark gray color, and contains recognizable solids.
• Approximately 99.9% water.
• Wastewater contains <0.1% total solids.
• BOD range: 300 - 500 mg/L
• TSS: 300 mg/L
• COD: 500 - 1000 mg/L

Industrial Sources

• Wastewater in which industrial wastewater predominates.

Population Growth Rate

Formula

• Pt = P0((1 + r)^t)
• Example:
  • P_0 = 43,128
  • P_t = 55,105
  • t = 9 \text{ years}
  • r = 0.0276

Linear Growth

• Pt = P0 + kt
• Example:
  • 55,105 = 43,128 + k(9)
  • k = 1330.777
  • P_6 = 51,113

Sewage Composition

• Includes sugar (polysaccharide), with rice having high sugar content.
• Proteins: When degraded, have a foul odor.
• Carbon & Hydrogen: Hydrocarbon
• Nitrogen and Phosphorus: Important because we design the treatment plant.

Oxygen

• Amount of oxygen dissolved.
• Saturated dissolved oxygen level: Max amount of DO.
  • Fish kill: Common in summer months.
  • Temperature = 25^\circ C
• Chemical oxygen demand: With carbon and hydrogen.

Solids

• Volatile Solids: Give up as gas during ignition.
• Fixed Solids: Remain after ignition.
• Dissolved Solids: Escape through the filter (dissolved in solution).
• Suspended Solids: Trapped by the filter.
• Colloidal Solids: Require coagulation treatment.
  • Coagulant: Chemical, positively charged to attract negatively charged colloids.
  • Composition: Typically 40% organic and 60% inorganic. Is truly dissolved

Total Solids

• Organic and Inorganic fractions.

Total Suspended Solids

Calculations

Percentage of Total Solids

• \% \text{ Total solids } = \frac{\text{Total solids weight}}{\text{Biosolids sample weight}} \times 100\%

Percentage of Volatile Solids

• \% \text{ Volatile solids } = \frac{\text{Volatile solids weight}}{\text{Total solids weight}} \times 100\%

Odors

• Caused by gases produced by the decomposition of organic matter.
• Fresh wastewater has a distinctive, somewhat disagreeable odor.
• Stale or septic wastewater: Characteristic odor of H_2S, produced by anaerobic microorganisms.

Effects of offensive odors:

• Poor appetite for food
• Lowered water consumption
• Respiration issues
• Nausea and vomiting
• Mental perturbation

Common Odorous Compounds:

• Amines: Fishy odor
• Ammonia (NH_3): Ammoniacal (pungent)
• Diamines: Decayed fish
• Hydrogen Sulfide (H_2S): Rotten eggs
• Mercaptans: Decayed cabbage, skunk
• Organic Sulfides: Rotten cabbage
• Skatole: Fecal matter

Key Properties

• Tyndall Property: Indicates cloudiness.
• Alkalinity: Important for wastewater, needs to be neutralized first.
• pH: Describes the acidity or basicity of a solution.

Decomposition

• Simplification via hydrolysis and saponification.
• Saponification: Reactions of fatty acids to calcium (foaming).

FOG measurement

• Measurement required to assess feasibility of biological treatment.
• Measurement of surface active agents.

Biochemical Oxygen Demand

Formulas

• yt = L0(1 - e^{-kt})
• ye = L0(1 - 10^{-kt})
• k = 2.303k \text{ days}

Temperature Correction for BOD

• kT = k{20}\theta^{(T-20)}
• Example: k_T = 0.23(1.047)^{(25-20)} = 0.29

TOC and Nitrogen

• TOC = Total Organic Carbon
• Total Carbon - inorganic carbon

Nitrogen in Wastewater

• Forms of Nitrogen:
  • Ammonia
  • Nitrate
• Includes organic nitrogen and ammonia.
• Process of increasing nutrients.
  • More algae (algal blooms)

Eutrophication

• Sum of all forms of Nitrogen
• Nitrification: Process of converting Ammonia to Nitrite to Nitrate.

Lake Aging

• Natural aging: Century
• Agricultural aging: Decade

Lake States

• Oligotrophic: Nutrient-poor
• Mesotrophic: Intermediate zone
• Eutrophic: Nutrient-rich

Undesirable Substances

• Substances that cause cancer and genetic mutations.
• Teratogenic: Causes malfunction to babies.

Wastewater Characteristics

Physical Characteristics

• Color: Indicates the condition of wastewater.
  • Fresh wastewater: Brownish gray
  • Typical wastewater: Gray and cloudy
  • Septic: Black

Types of Color

• Apparent Color: Due to suspended solids.
• True Color: Due to dissolved solids that remain after suspended solids.
• Odor: Caused by gases produced by decomposition of organic matter or other substances.
• Temperature: Sewage temperature is higher than water supply.
  • Mean annual wastewater temperature: 10 to 21.1°C
• Turbidity: Degree of cloudiness or haziness of a solution.
  • Measure of the light-transmitting properties of water.

Chemical Characteristics

• pH: Measures the acidity or basicity of a solution.
• Alkalinity: Measure of the wastewater's capability to neutralize acids.
  • Measured in terms of bicarbonate, carbonate, and hydroxide alkalinity.
• Acidity: Capacity to neutralize bases.
• Biochemical Oxygen Demand (BOD): Measure of the amount of biodegradable matter.
  • Normally measured by a 5-day test conducted at 20°C.
  • BOD5 of domestic waste: 100 to 300 mg/L.
• Chemical Oxygen Demand (COD): Measure of the amount of oxidizable matter.
  • COD: 200 to 500 mg/L.

Solids

• Most pollutants found in wastewater can be classified as solids.
  • Organic solids: Consist of C, H, O, N and can be converted to CO2 and water by ignition at 550°C. Also known as volatile solids or solids loss on ignition.
  • Inorganic solids: Mineral solids that are left after ignition. Also known as fixed solids or ash.
  • Dissolved solids: Also known as Non-filterable solids, are solids that will pass through a glass fiber filter pad. Can be classified as TDS, VDS and FDS.
  • Suspended solids: Filterable solids are solids that can be filtered out, including settleable solids and non-settleable solids (colloids). Can be classified as TSS, VSS and FSS.

Other Organic Matter

• Proteins (40-60%): Principal constituents of the animal organism.
• Carbohydrates (30-50%): Include sugars, starches, cellulose, and wood fiber.
• Fats, Oil and Grease (10%): Sources are animal and vegetable matter.

Nitrogen

• Most of the nitrogen in untreated wastewater will be in the forms of organic nitrogen and ammonia nitrogen.
• Total Kjeldahl Nitrogen (TKN): Sum of organic nitrogen and ammonia nitrogen.

Wastewater Composition

• Total Nitrogen: 20 to 85 ppm
• Organic N: 8-35 ppm
• NH3 N: 12-50 ppm

Phosphorus

• Essential to biological activity and must be present for secondary treatment processes.
• Phosphorus concentration: 6-20 ppm

Biological Characteristics

• Bacteria: Single-celled microorganism, most important in biological treatment.

Types according to carbon requirement

• Autotrophic: Carbon source is inorganic CO_2
• Heterotrophic: Carbon source are organic matter
• Protozoa: Motile, microscopic protists

Groups of Protozoa

• Sarcodina: Having pseudopods or false feet.
• Mastigophora: Flagellated protozoa
• Sporozoa or apicomplexan: Spore-forming protozoa
• Ciliata: Free-swimming and stalked type
  • Fungi: Multicellular, non-photosynthetic, heterotrophic protists.
  • Coliform organisms: Rod-shaped bacteria thriving inside the intestinal tract of man.
• Indicator that pathogenic organisms may also be present.
• Genera include Escherichia and Aerobacter.
• Other genera: Citrobacter, Hafnia, and Klebsiella
• E.coli is the preferred pathogen indicator.

Accepted Methods for determining the number of Coliform organisms

• MPN - Most Probable Number Technique
• MFT - Membrane Filter Technique
  • Algae: Photosynthetic organisms significant in pond systems.
  • Macroscopic organisms:
• Rotifers: Aerobic, heterotrophic, and multicellular animal. Indicates a highly stabilized biological process.
• Crustaceans: Having hard body or shell. Indicators of stabilized wastewater (require high DO to survive).
  • Virus:
• Not considered as biological microorganism but as entity only since they are dependent on their host to survive and to replicate.

Typical Domestic Wastewater Characteristics