WATER POLLUTION BOD WHAT IS IT Biodegradable organic

WATER POLLUTION

BOD: WHAT IS IT? • Biodegradable organic matter • Excess is consumed by bacteria in the water • They deplete the water of oxygen • Example: Gold fish bowl

WHAT CAUSES A BUILDUP OF BOD • Fall leaves • Animal/human waste discharge • Process plant discharge-especially in food manufacturing

CONDITIONS THAT CAN CAUSE ELEVATED LEVELS • Water temperature increases causing the bacterial population to increase • If sufficient organic material is present in the water

HOW CAN YOU MEASURE IT • Chemists mix water with “organics” with oxygen and test how long it takes for the oxygen levels to drop • This test is typically 5 days at a lab • COD testing is another route • Much more cost effective • Quicker results • Can be done in house

MARCH 2016: FLORIDA FISH KILL

WHAT IS EL NINO? • Climate cycle begins in the Pacific Ocean • Warm water from the western tropical Pacific ocean shifts eastward along the equator of South America • Forcastors declare an official El Nino when they see both ocean temperature and rainfall veer towards the east • Happens every 3 -5 years

2015 -2016 EL NINO • Super El Nino • Hottest summer yet (2011 -2015 warmest summers) • Sea surface temperatures peak around December, impact is usually seen a few months later as the global ocean heats up • 2015 hottest year ever without El Nino, but El Nino caused a 810% increase in temps as well

EL NINO • Causing massive algae bloom • Pseudo-nitzschia genus produces a deadly neurotoxin • Builds up in sediment and sea-life • Warm water in the Pacific (The Blob) combined with nutrient rich water of Pacific coast=perfect conditions • Duration of algae blood precedented

ALGAE BLOOM COMPLICATIONS • Fish kills • Amnesic shellfish poisoning • GI issues • Vomiting and diarrhea after ingestion • Must be monitored and communicated in the summer during blooms • Dungeness crab/clamming

HORMONE DISRUPTORS AND DRUGS • Pulp mills release estrogen-like compounds in significant amounts into lakes and rivers • Changes the hormonal system of the animals that ingest them • When fish are exposed to these hormones, male fish develop both male and female reproductive parts • Female birth control pills

HORMONE DISRUPTORS AND DRUGS • Paper mills release group of potentially harmful materials know as dioxins • High levels are carcinogenic • Low levels will suppress the immune systems of animals/humans • Some have converted to chlorine free processes, but very little have converted thus far

SEWAGE TREATMENT AND DISPOSAL • Primary sewage treatment • Secondary sewage treatment • Tertiary treatment

PRIMARY SEWAGE TREATMENT • Settling tanks (Clarifiers) • Removes solids from water/fluid chlorinated and discharged • Travel through screens when it enters the plant • Sludge is pumped to the digester • Bacteria feed on it • Methane gas is produced-can be burned off • Primary treatment removes 30 -60% BOD

SECONDARY TREATMENT • Aerobic bacteria to break down degradable organic materials • Removes ammonia to nitrates • Activated Sludge Process • Trickling Filter

ACTIVATED SLUDGE PROCESS • Fluid is pumped out of the clarifier into another tank that is aerated • Aerobic bacteria breakdown • BOD drops rapidly due to increase oxygen and aerobic bacteria • Then transferred to settling tank • Remaining suspended material and bacteria sink to the bottom

SLUDGE DIGESTER • Sludge is transferred to the anaerobic digester • It is broken down to activated sludge due to the lack of oxygen • Some is recycled back to aeration tank to seed the tank • What is left is dried and can be used as a fertilizer or go to the landfill

TRICKLING FILTER • Sewage is sprayed by arms that are slowly rotating onto a filter bed of stones • Stones are covered with thin film to help dissolve organic compounds • Solids are transferred to sludge tank • 80 -85% of dissolved organics are removed

TERTIARY TREATMENT • Removes nitrates and phosphates • Not all waste water systems have tertiary treatments • Four times as expensive to operate • Currently 50% of treatment plants have tertiary treatment

RECYCLING WASTE • Fuel • Biogas used to run sewage • Livestock feed • Proteins and fats that are required • Soil fertilizer • Land apply