Section Eleven- Wastewater Collection and Treatment

Total infiltration / inflow

wet weather flow - sanitary flow

total WWQ during periods of little to no rainfall, consist only of sanitary flow and groundwater infiltration(in GW level is higher than sewer invert and presence of crack)

dry weather flow

if there is no infiltration dry weather flow=

sanitary flow

for a specific period of no rainfall, difference between the wet and dry weather flow is the _____

infiltration

wet weather flow- dry weather flow or wet weather flow - sanitary flow

infiltration

sanitary , groundwater, rainfall dependent infiltration / inflow

wet weather flow

max hourly inflow is determined graphically as the difference between the peak hourly wet weather flow , and the ________

COMPARABLE FLOWRATE ON THE PRECEDING DAY

total daily flowrate

multiply flow x time interval

average daily flowrate

total flow / 24 hours

gallons per capita flow (population 10,000)

average daily flowrate/ population

gallons per capita flow per day (gpcd)

the daily flow divided by the population determine the wastewater flow produced per person per day

average over a 24-hour period based on annual flow rate. Used in evaluating treatment plant capacity design .

average daily flow

largest flow over a 24 hour period based on annual operating data . Important for retention time, equalization basins

max daily flow

largest accumulation of flow in an hour during a particular day as obtained from oan exhaustive length of flow record.

peak hourly flow

flow rate that is sustained or exceeded for a specified number of consecutive tmie periods

sustained peak flow rate

How to determine waste water flow versus stormwater flow

1.) waste water flow = average , peak , design Q

2.) Q= CIA

present rate of peak sewage flow is 10 MGD, which is expected to increase to 15 MGD at end of 25 years, flow to design diameter , and flow to check the velocity

15 MGD for diameter, 10 MGD for velocity

common type of operation, monitoring and maintenances

odor control, corrosion, smoke testing, grease and trash removal,, scum control

potentenial sources of odor

hydrogen sulfide (H2S) dominent odor , other sulfur , nitrogen, organic compounds

absorption

capture by water or other fluids

capture by activated carbon

adsorption

oxidation by microorganisms

biological

oxidation of odor components

chemical

help identify areas where unauthorized water is entering the sanitary sewer system

smoke testing

sewer pipe is design for (max flow, min flow, average flow only, max and min flow)

max flow = diameter, min flow = velocity

activated carbon is used for (disinfection, hardness, odors, corrosiveness)

odor control

measure of the amount of light that is absorbed by the sonstituents in the solution at a given wavelength

absorbance

fractional relationship of the intensity of the transmitted light through a solution and pure solvent

transmittance

treatment objective that is remove pathogen

sedimentation

treament objective that remove/reduce suspended solid

air stripping

treatment objective that remove/reduced VOC

UV

mechanical process used to remove oil and most of setteable solids. A 25-35 % reduction in BOD is also achieve

primary treatment

involves biological treatment in trickling filters , rotation contractiors, biological beds, and activated sludge process. Reduces the suspended solids and BOD content by more than 85%

secondary treatment

removes specific pollutant or wastewaster character

tertiary treatment

operation to eliminate or minimize fluctiuation in waterwater flow and characteristic

equalization

particles that settle discretely at a constant settling velocity (grit chamber- sand and grit removal, PRIMIARY SEDIMENTATION TANK setting

Discrete particle settling (gravity settling)- Type 1

Particle that flocculate during sedimentation. Particle sizes changes, hence, so does velocity . COAGULATION, TRICKLING FILTRATION

Flocculent settling -Type 2

portion of the flow leaving the basin at later time which could be due to temperature and wind actions

short circuiting

results in a portion of the flow leaving the basin at later time which could be due to temperature and wind condtions

dead zones

causes of density currents (2)

1.) a cold source water enters a basin of warmer water 2.) a warm source water enter a basin of colder water

laminar flow the drag oefficient will increase with the ____ of the Re (increase, decrease , both A &B, none)

increase

as wastewater enters a sedimentation basin, which of the flow distributons is important to achieve proper velocity throughout the basin (uniform, non uniform, or turbulent)

unifrom

in bio treatment the ____ or ____ food / substrate serves as a electron donor to BACTERIA

organic matter , hydrocarbon

in bio treatment, oxygen , nitrate / nitrite , sulfate or CO2 serves as the ____

electron acceptor

secondary treatment (biological) purpose

1.) to remove the soluble BOD that escapes primary treatment 2.) provide further removal of suspended solids

secondary treatment (biological) factors

1.) availability of microorganism and oxygen, 2.) good contact between the organic matter and microorganism, 3.) favorable enviormental condition (sufficient temperature, and time)

secondary treatment systems

activate sludge, oxidation pond (lagoon), trickling filter, roating biological contactor

wastewater treatment process in which the microorgnaisms and bacteria treating the waste are suspended in the wastewater being treated

aerobic suspended growth system

biological treatment processes that employ a medium such as rock, plastic, wood, or other natural or syntheic solid material that will support biomass on its surface and within its porous structure

attached growth system (fixed film system)

cell growth stages

lag phase, exponential (logarithmic) growth phase, the declining phase , the maximum (stationary) phase, and the death phase

major microorganisms in the "living" system of secondary wastewater treatment

bacteria and protozoa

______ are desirable in wastewater effluent because they act as polishes by consuming remaning bacteria

protoza

agitate and aerate mixture of wastewater and bio sludge (microorganisms) . Compressed air injected continuously into mix through porous diffueres located at bottom of tank

purpose of aeration tank

as microorganisms grow and are mixed by agitation of air, indivudal organisms flocculate to form active mass of microbes (bio floc)

activated sludge

SS in aeration tank are mix of activated sluge and ww in aeration tank. MLSS consist of microorganisms, non biodegradable suspended organic matter, and other inert suspended matter

MLSS

most of the settled sludge in secondary clarifier is returned to the aeration thank to maintain the high population of microbes that permits rapid breakdown of organic matter

Return activated sludge

some portion of activated sludge is discarded to maintain the propoer amount of microranicms to efficiently degrade BOD5

Waste activated sludge

it is the ratio of average amount of the that solids (microorganisms) are kept in the reactor dived by mass of organisms removed from the system each day

mean cell residence time/ solid retention time, sludge age

mass of oxygen/ day equation

total mass BODU used - 1.42 (mass of organisms wasted Px)

electron accpetors

O2, NO3, SO4

under aerobic decomposition ___ must be present as the terminal ____

O2 and electron

chemical end products of aerobic decomposition

carbon dioxided , water and new cell products.

under anoxic decomposition microorganisms use ____ as the terminal ______

nitrate NO3, electron

chemical end products of anoxic decomposition

nitrogen gas, carbon dioxide, water, new cell material

under anaerobic decomposition _______MUST NOT BE PRESENT. as the terminal ______

O2 and nitrate , ELECTRON ACCPETORS

chemical end products of ANAEROBIC decomposition

Sulfate , CO2, organic compounds

Class A biosolids

pathogen free

Class B biosolids

detectable levels of pathogens

Befitis for sludge thickening

tank capacity, decreases, # chemicals req decrease, heat required by digesters decrease, reduction of pipe size/ pump cost

used to thicken WAS, and Suspended growth nitrifcation sludge. Ability to thicken particles of small size and density close to fluid. Introduce bubbles that attach to solid then rise to surface

dissolved air flotation

sluge treatment purposes (3)

1.) reduce pathogens, eliminate odor, elimate rot/ putrefaction

alkaline (lime) dignestion treatment for sludge

add hydrated lime or quick lime to raise PH to 11 + to reduce odor which help kill pathogens

anaerobic digestion treament for sludge

bio conversion of organic matter by fementation to produce methane gas and co2 , OOCURS DURING PRESENCE OF O2 ( standard rate, high rate and two rate digestion)

aerobic digesion treatment for sludge

bio conversion of organic matter in presence of air or oxygen

treatment of effluent for destruction of all pathogens and microorganisms, no attempt for sterilization, bacteria numbers reduce to safe level

disenfection

most important variable in disinfection process

contact time

factors/ varibles imporant in disinfection proectess

contact time, concentration/ chemical agents, intensity and nature of

physical agents, temp, # or organism

at ph ___ hypchlorous and hypochlorite ions will be present in equal numbers

7.3

Chlorine Dose (mg/L)=

Chlorine demand (mg/L) + Chlorine Residuals (mg/L)

cause turbidity and color in water and wastewater

colloidals

substances (such as lime) added to water in addition to primary coagulatnt to enhance process - control PH, etc.

coagulant aid

chlorine residuals (mg/L) =

combined chlorine form (mg/L) + free chlorine (mg/L)

free chlorine is equal to =

HOCl + OCl-

combined chlorine is equal to =

NH2Cl + NHCl2 + NCl3

UV does D is defined as

D=I x t

blue / colorless unstable gas at the temp and pressure encountered in water and waste water treatment process. It has a pungent odor ozone is one of the most powerful oxidization agent. Used for NITRIFICATION

ozonation

chlorine demand of water is equal to

difference of chlorine dose and residual chlorine

advance wastewater treatment includes

nitrogen , phosphorus, and heavy metals

nitrogen removal methods

nitrification/ denitirifaction, ion exchange, break point chlorination, gas striping, overland flow

phosphorus removal method

chemical precipitation (coagulation) / biological treatment

suspended solids removal method

chemical coagulation, filtration

Total Kjeldahl nitrogen (TKN)

Combination of ammonia and organci nitrogen concentrations

remove the nitrate that is formed during nitrifcation

denitrification

denitification requires an ____ enviorment

anoxic

denitifiying microorganisms that reduce nitrate to nitrogen gas that is released into the atmosphere is considered ______

heterotrophic

biological oxidation of ammonia to nitrate with nitrrite formation as an intermediate step

nitrification

post denitification

BOD and ntirifcation first in AEROBIC then denitrifcation in ANOXIC

first pass through ANOXIC denitification zone then AEROBIC nitirfication and BOD removal zone

pre denitirficiation

advance wastewater treament is used for

N&P removal, toxic metals, additional organic and suspended solids removal

Which is associated with corrosion of sanitrary sewers (H2S, BOD, Fats / oils/ greases, NH3)

H2S