DEFINITIONWASTE WATERPOLLUTION OF RECEIVING WATERWASTEWATER COLLECTION

Water PollutionIt is an imprecise term that reveals nothing about either the type of polluting material or its source

Water pollution occurs when a body of water is adversely affected due to the addition of large amounts of materials to the water. When it is unfit for its intended use, water is considered polluted.

POINT SOURCES

pollution of our water resource can occur directly from sewer outfalls or industrial charges

occur when harmful substances are emitted directly into a body of water.

Ex: Oil spill best illustrates a point source water pollution.

OIL SPILL CLEAN-UP

NONPOINT SOURCES

indirectly from air pollution or agricultural or urban runoff.

delivers pollutants indirectly through environmental changes.

Ex: when fertilizer from a field is carried into a stream by rain, in the form of run-off which in turn effects aquatic life

Waste Wateralso called sewage

a complex mixture containing water (usually over 99%) together with organic and inorganic contaminants, both suspended and dissolved.

Wastewater may contain microorganisms which may be either harmless or which can cause diseasesPATHOGENS (disease-causing organisms).

WATERBORNE BACTERIAL DISEASES: Cholera Typhoid Tuberculosis

VIRAL DISEASES: Infectious hepatitis Protozoan-caused dysentery

PATHWAYS OF CONTAMINATION

The total solids (organic plus inorganic) in wastewater.

Chlorides and sulfates normally present in water and in wastes from humans

Nitrogen and phosphorus forms in wastes from humans, with additional phosphorus detergentsCarbonates and bicarbonates normally present in water and wastes as calcium and magnesium salts Toxic substances arsenic, cyanide, and heavy metals found in industrial wastes

90% are proteins and carbohydrates sources of biodegradable contaminants are excreta and urine from humans, food wastes from sinks, soil and dirt from bathing, washing and laundering various parameters are used as a measure of the organic strength of wastewater.

1. TOC (total organic carbon) determined by measuring the amount of CO2 produced when the organic carbon in the sample is oxidized by a strong oxidizing agent and comparing with the amount in a standard of known TOC2. COD (chemical oxygen demand) the measured amount of oxygen needed to chemically oxidize the organics presentMeasurement of organic strength of wastewater

The 6800 Series Total organic carbon analyzer

3. BOD (biochemical oxygen demand) the measured amount of oxygen required by acclimated microorganisms to biologically degrade the organic matter in the wastewater

Lt = Lo e-kt CBODt = Lo ( 1-e-kt)Where:Lt = carbonaceous BOD remaining at time t=t(O2 needed to oxidize carbonaceous organic matter remaining)Lo = ultimate carbonaceous oxygen demand (ultimate BOD; O2 needed to oxidize carbonaceous organic matter initially present)CBODt = carbonaceous oxygen demand (BOD satisfied; O2 used to oxidize carbonaceous organic matter at t=t)t = time (days)k = rate constant (base 10) per day

The Model T2800 On-line TOD/COD

BOD curve at 20oC Carbonaceous + Nitrogenous Oxygen DemandLo Ultimate Carbonaceous Oxygen Demand CBODt = Carbonaceous Oxygen Demand L= Carbonaceous BOD Remaining 246810121620

kT = (T-20) k20

= 1.047 T = temperature (oC)k20 = reaction rate constant at the standard lab TkT = reaction rate at a different T

BOD Removal Rate Constants

DO (dissolved oxygen) the amount of oxygen dissolved in surface watersThOD (Theoretical oxygen demand) the amount of oxygen needed to oxidize an organic matter to CO2 and H2O if the composition of the organic matter is knownBOD5 the total amount of O2 consumed by the microorganisms during the 1st 5 days of biodegradation

Conditions in Measuring BOD5

light must be kept out of the bottle to keep algae from adding oxygen by photosynthesisstopper is used to keep the air from replenishing DO that has been removed from biodegradationsample must be diluted

BOD5 = DOi DOf pwhere DOi = initial DO of the diluted waste water DOf = final DO of the diluted waste water P = dilution factor = vol waste water / vol wastewater + dilution water

Sample Problems:

A 10.0-mL sample of sewage was mixed with enough water to fill a 300-mL bottle has an initial DO of 9.0 mg/L and a final Do of 2.0 mg/L. What is the BOD5?The dilution factor for an unseeded mixture of waste and water is 0.030. The DO of the mixture is initially 9.0 mg/L, and after five days it has dropped to 3.0 mg/L. The reaction constant k has been found to be 0.22/day. A. What is the five-day BOD of the waste? B. What would be the ultimate carbonaceous BOD? C. What would be the remaining oxygen demand after five days?

Biochemical Oxygen Demand (BOD) of Pasig River

BOD levels from 1999 to 2000 have decreased in nearly all stations. Station 7 (downstream San Juan River), however, was still beyond the BOD standard of 1mg/L for class C waters.

conformancenon-conformance

includes employees sanitary wastes, process wastes from manufacturing, wash waters, and relatively uncontaminated water from heating and cooling operations.

Wastewater Treatment

less contaminated compared to municipal wastewater.

Quantity of storm water runoff from a municipality varies widely with the time of year, type of terrain, and intensity and duration of the storms that occur.

Pollution of Receiving Waters POLLUTANTS in RECEIVING WATERS

PathogensOrganic matterSolidsNutrientsToxic and hazardous substancesOther Pollutants

Primary Treatment - during primary treatment, a large percentage of the suspended solids and inorganic material is removed from the sewage.

Secondary Treatment - the focus of secondary treatment is reducing organic material by accelerating natural biological processes.

Tertiary Treatment - is necessary when the water will be reused; 99 percent of solids are removed and various chemical processes are used to ensure the water is as free from impurity as possible.

Wastewater CollectionEARLY SYSTEMS

Roman Times widespread use of sewers occurredPipes were installed to carry away storm water from the streets Problems with combines sewers led to the concept of separate sewers: one system for storm water and one for sanitary wastes.

PRESENT SYSTEMS

sewage collection today normally consists of separate storm and sanitary sewers in the newer areas and combined sewers in the older sections of cities.

Sanitary sewers are underground pipes that collect domestic and industrial wastewater and convey them to a treatment facility.

Sanitary Sewers provide service for domestic and industrial wastewater do not provide drainage for roof leaders or yard drains In older areas, drain weeping tile systems (now prohibited) convey peak dry weather flow plus groundwater to treatment plant must now also consider infiltration/inflow which can be significant.

Sanitary sewers must be designed to handle the peak rate of flow.

Storm sewers are underground pipes that collect street and yard drainage and discharge the collected water to a surface watercourse, lake or ravine.

Storm Sewers provide convenience drainage for roads and adjacent properties are designed for a specific storm event (e.g. 1 in 5 year rain storm) provide an economic balance between flooding and construction costs in conjunction with major drainage systems, provide greater protection in newer areas.

building with basements are protected against high groundwater levels by installation of perforated or open jointed drainage pipes laid in a gravel trench around the basement footings.The uncontaminated water collected by these foundation drains may then discharge to:a storm or combined sewer if sewer backup is unlikely

(2) A sanitary sewer or basement sump

(3) A separate foundation drain collector

Combined sewers are underground pipes that collect domestic sewage, industrial wastewater and storm water.

Perform the functions of sanitary and storm sewers.

In dry weather all flows collected by combined sewers are delivered to a wastewater treatment facility.

In wet weather some flow collected by combined sewers is delivered to the treatment facility through the interceptor sewers and the rest is spilled to the surface through combined sewer overflows.

Combined Sewers

provide basic sanitary service for domestic and industrial wastewater provide convenience drainage for roads and adjacent properties exist in over 1200 communities across North America provided economical servicing made sense in horse & buggy days are not good modern practice eliminating is expensive.

Combined Sewer Overflows (CSO's)

protect homes and streets from flooding during storms spill diluted sewage to the river during storms are not environmentally friendly quantity of flows spilled and frequency of spillage are expensive to reduce.