Wastewater

Domestic sewage

the combination of blackwater and greywater from households

Non-sewage

wastewater from commercial, industrial, agricultural, and institutional sources, wach with its own specific characteristics and potential pollutants

Sanitary sewer systems

designed to carry wastewater from homes and businesses to a wastewater treatment plant. this includes from toilets, sinces, showers, and other drains

stormwater sewer system

collect rainwater runoff from streets, roofs, and other surfaces and transport it to rivers, lakes, or the ocean.

this water is typically untreated

Combined Sewers

older systems in some cities combine both sanitary sewage and stormwater runoff in the same pipes. This can be problematic during heavy rain, as the system can overflow, releasing untreated sewage into the environment

Tunnel and Reservoir Plan

captures and stores combined stormwater and sewage that would otherwise overflow from sewers into waterways in rainy weather.

The stored stormwater will be treated via the Standard Municipal Treatment Process before release

Septic system

self-contained wastewater treatment systems used in individual homes or small communities that are not connected to a centralized sewer system.

The solids stay in the tank while the wastewater is discharged to the drainfield for further treatment and dispersal

Case Study: Long Island, New York

After WW2, developers built massive suburban communities withh speetic systems on long island.

More than 360,000 homes in Suffolk County rely on outdated cesspools and septic systems that do not properly treat wastewater to remove nitrogen → the ground is saturated with nitrogen.

Studies show that declining water quality that has closed beaches, caused brown tides and fish kills is caused by excess nitrogen, and that cesspools and septics are the larget source of nitrogen pollution.

The “indicator” species:

we test for Fecal Coliforms and Enterococci. If they are present, it guarantees that more dangerous pathogens are also there.

Ingestion

Accidental swallowing during floods causes Gastroenteritis

Skin Contact

floodwater entering small cuts causes Staph infections or tetanus

Aerosolization

inhaling spray from aeration tanks or rough surf can cause repiratory illness

Beach Closures

if Enterococcus levels >104 CFU/100mL (EPA limit), the beach closes

Boil Water notices

If floodwater enters the municipal supply pipes, the entire city must boil water to kill the bacteria

Preliminary Treatment

removes large debris like sticks, rags, and plastics using bar screens or mesh screens. Settles out heavy inorganic materials like sand and gravel in grit chambers

Primary Treatment

uses gravity to settle out suspended soilids, forming a sludg layer at the bottom of primary clarifiers. Remove lighter materials like greate and oit that float to the surface.

Secondary Treatment

1. Employs microorganisms to break down organic matter in the wastewater → key step for Biochemical Oxygen Demand reduction.

2. Removes remaining suspended solids and some dissolved organic matter using sand filters, membrane filters, orother filtration technologies.

   1. Kills or inactivates disease-causing orgnaisms using chlorine, ultraviolet light, or ozone.

Influent

Measure BOD as the raw sewage enters the plant to see the total “load”. This step tells the operators how much “food” is available for the bacteria in the secondary step.

Primary Effluent

After physical settling, BOD is measured again. Primary treatment usually removes 25-40% of BOD.

Secondary Effluent

This is the critical test. Secondary treatment uses bacteria to “eat” the dissolved orgnaic matter that physical settling could not catch. By this stage 85-95% of the BOD should be gone.

Tertiary Treatment (optional in many places)

1. Removes nitrogen and phosphorous to prevent eutrophication in receiving waters.

2. May be other processes to further remove contaminants

Who uses this system? Cities near vulnerable ecosystems or recycle water resources

MARPOL

International Convention for the Prevention of Pollution from Ships.

Includes regulations aimed at preventing and minimizing pollution from ships-both accidental pollutions and from routine operations.

six Annexes of MARPOL

Annex I: Rgulation for pollution prevention by oil

Annex II: Regulation for controlling pollution by Noxious Liquid Substance in Bulk

Annex III: Regulation for preventing pollution by harmful substances carried at sea in packaged form

Annex IV: Regulation for pollution prevention by sewage from ships

Annex V: Regulation for pollution prevention by garbage from ships

Annex VI: Regulation for prevention of Air pollution from ships

Cartagena Convention

To protect and develop the marine environment of the Wider Caribbean Region

To promote regional cooperation among countries in the area

To address pollution from various sources, including land-based and sea-based activities.