General Wastewater and A1 Biological Treatment: Suspended Growth Processes

Define biochemical oxygen demand (BOD)

(mg/L) is a measurement of the organic strength of a sample by measuring amount of oxygen consumed over time

Define composite sample

a sample prepared by combining a number of grab samples, typically over a 24 hour period

Define dissolved oxygen (DO)

(mg/L) is the measure of the amount of oxygen dissolved in water

Define effluent

treated wastewater discharged from a treatment plant to the environment

define eutrophication

excessive growth of plant and algae in receiving waters due to dissolved nutrients and their decomposition

Define flume

a restriction

define food to microorganism ration (F:M or F/M)

the amount of food (BOD) provided to the microorganisms in the MLSS

define grab sample

a single sample taken at a particular time and place that is representative of the current conditions

define hydraulic retention time (HRT)

a period of time that wastewater remains in a tank, also known as detention time

define influent

the raw or untreated wastewater entering a treatment process

define septage

the high strength waste pumped out of septic tanks

define sludge age

theoretical length of time a particle stays in the plant, measured in days. lbs of MLSS divided by lbs of WAS per day

define total suspended solids (TSS)

the measure of the total amount of solids suspended in a sample (mg/L)

define weir

level control structure used to provide uniform flow

define combined sewer

pipes that carry both wastewater and storm water

define inflow and infiltration (I/I)

any unwanted clearwater that leaks into a collection system

define lift station

an underground chamber with pumps that is used to lift wastewater

define manhole

a structure that provides access to a collection system

define sanitary sewer or collection system

underground pipe system used to convey wastewater to a treatment facility

Define sanitary sewer overflow (SSO)

a release of wastewater from a collection system directly into a water of the state. must be reported within 24 hours

Define storm sewer

an underground pipe system that collects rainwater streets and takes it somewhere other than a wastewater treatment plant

define treatment facility overflow (TFO)

a release of wastewater from a wastewater facility into a water of the state. must be reported within 24 hours

define wet well

a tank where wastewater is collected

define aeration basin

a tank where wastewater is aerated

define aerobic (oxic)

a condition under which free and dissolved oxygen is available in an aqueous environment

define anaerobic (septic)

a condition under which free, dissolved, and combined oxygen is unavailable

define anoxic

a condition under which oxygen is only available in a combined form in an aqueous environment

define biosolids

nutrient-rich organic byproduct of a wastewater treatment plant

define clarifier

circular or rectangular tank used to remove floatable and settleable solids in wastewater

define disinfection

a process used to destroy most pathogens in effluent

define grit

fine, abrasive particles removed, such as sand and eggshells

define headworks

the beginning of a treatment plant where influent flow is measured

define microorganism

a living organism to small to be seen with the naked eye

define primary treatment

a process usually consisting of clarification removing a substantial amount of suspended and floating matter

define process control

the tools and methods used to optimize treatment plant operationsde

define return activated sludge (RAS)

the settled biomass collected in a final clarifier and returned to the treatment process. returns microorganisms to the aeration basin

define screenings

the materials in wastewater removed with screens

define secondary treatment

a process using bacteria to remove pollutants

define selector

part of the treatment system that selects for a specific type of microorganism by providing an environment (anaerobic, anoxic, aerobic) that favors its growth

define sidestreams

flows generated within the plant, usually from recycled solids

define tertiary treatment

a process using physical, chemical, or biological processes to removed suspended solids and nutrients in wastewater better than secondary

define treatment process

a physical, biological, or chemical action that is applied to wastewater to removed or reduce pollutantsd

define treatment unit

an individual structure or equipment within a collection system or wastewater treatment facility that is part of a treatment process

Define waste activated sludge (WAS)

the activated sludge removed from the secondary treatment process

define confined space

a space large enough for an operator to enter and perform assigned work. limited means for entry and exit

define pathogens

infectious microorganisms in wastewater that pose health risks

define Wisconsin Pollutant Discharge Elimination System (WPDES) permit

issued to wastewater facility owners and contains limitations, conditions, and reporting requirements

discuss where a wastewater operator would find info on tests

Standard Methods for the Examination of Water and Wastewater, first published in 1905

Discuss early historical methods of dealing with wastewater

disposal directly onto land surface, in gutters and ditches. Later development of pit toilet led to collection systems. eventually pipe systems took wastewater away from human habitation and to a water body. improved health concerns, transferred problem to water streams

discuss Clean Water Act

a federal law created in 1972 with the main objective of chemically, physically, and biologically restoring and maintaining waters. created to stop continuous dumping of pollutants into surface waters and wetlands

discuss importance of treating wastewater

protect public health by destroying pathogens

protect environment by removing pollutants

describe sources of wastewater

down the drain from domestic, industrial, and commercial sources

list and define common sources of I/I

roof leaders

storm and sanitary crossovers

low lying manholes

uncapped lateral connections

sump pumps

crcks and offset joints in sewer

manhole cracks and defects

buried manholes

cracks and leaks in building sewers

discuss effect of I/I on a collection system

can exceed flow capacity of pipes and cause surcharging, backups and SSO. High flows at plant, washed out solids

explains components of a sanitary sewer collection system

private building lateral sewer

mainline sewer

force mains

lift stations

inverted siphon

manholes

discuss operation and maintenance of a collection system

cleaning

root removal

televising

flow monitoring

smoke testing

manhole inspections

lift station maintenance

manhole rehab

mainline rehab

private sewer inspecitons

private sewer I/I removal

fat, oil, and grease (FOG) control program

describe characteristics of influent domestic wastewater

less than 99% water, gray, musty odor

Discuss control measures necessary for industrial discharges

enforce sewer use ordinances

effective communication

grease control program

monitoring

types of materials prohibited from discharge into collection systems

volatile organics like gasoline and solvents

heavy metals

pH lower than 5 or greater than 10

FOG

high strength BOD or suspended solid loadings

high temp waters

solid or viscous materials

debris like rags

toxic materials

discuss info that must be recorded for influent samples

sample identification

date started

time started

date collected

time collected

sampler temperature

operator initials

comments

explain why some treatment plants have ammonia nitrogen limits

toxic to fish and aquatic life

explain total phosphorus limits

key nutrient contributing to eutrophication and algae and plant growth

describe role of microorganisms in activated sludge process

convert dissolved and particulate organic matter into cell mass. use oxygen to break down organic matter to increase cell mass

photosynthesis equation

CO2+2H2O => CH2O+H2O+O2

types of pumps used

centrifugal pump

submersible pump

positive displacement piston pump

rotary lobe pump

peristaltic pump

progressive cavity pump

airlift pump

diaphragm pump

trash pump

Energy usage

aeration is 60%

pumping is 12%

NR 204

domestic sewage sludge management

NR 214

Land treatment of industrial liquid wastes, by-product solids and sludges

prevalent diseases taht can be contracted through wastewater exposure

gastroenteritis

dysentery

hepatitis b and c

giardiasis

upper respiratory illnesses

toxic wwtp gases

hydrogen sulfide

methane

carbon monoxide

chlorine

define denitrification

biological process where bacteria convert nitrate and nitrite to N2 gas under anoxic conditions

define floc

clusters of microorganisms and solid particles that form in the activated sludge process and settle in the final clarifier

define marbling

the variegated, marble stone like appearance on a quiescent part of an aeration basin as a result of good floc and water separation

define nitrification

a biological process where nitrifying bacteria convert nitrogen from ammonia to nitrite and nitrate

define protozoa

single celled organisms that require oxygen and eat bacteria. includes amoeba, flagellates, ciliates

define sludge blanket

layer of solids on bottom of clarifier

define sludge volume index

numerical expression of settling characteristics of activated sludge. good value is 100, could be between 80 and 150

desired ratio BOD:N:P

100:5:1

describe types of protozoa and organisms in MLSS

amoebae, free swimming and stalked ciliates, flagellates, and suctoreans. also rotifers

conditions that favor filamentous organisms

low DO

low F:M ratio

low pH

high sulfides

nutrient deficiency

excessive grease

conditions necessary for nitrifying bacteria

DO greater than 1.0

pH between 7.0 and 8.5

alkalinity greater than 50 mg/L

temp between 50F and 85F

environmental conditions needed for denitrifying bacteria

DO less than 0.2

pH between 7.0 and 8.5

adequate organic matter

temp between 50F and 85F

operational modifications from summer to winter

increase MLSS concentration

winterize equipment

define bulking

activated sludge that does not settle well and may overflow the weirs of the final clarifiers resulting in excess suspended solids in the effluent. usually caused by filamentous organisms

define filaments

a group of thread-like organisms that can impair settling

hydraulic load

flow entering plant, measured in MGD

define pin floc

very fine floc that settles poorly, indicative of old sludge

define short circuiting

uneven flow distribution in a wastewater tank. detention time is less in some parts than others

define straggler floc

small, light, fluffy floc that settles poorly, indicative of younger sludge and/or low MLSS

difference between MLSS and MLVSS

all suspended solids vs only organic amount

common indicator organisms

amoeba

flagellates

free swimming ciliate

crawling ciliate

community stalked ciliate

rotifer

filamentous organism

three factors that affect DO in aeration basins

BOD loading

temp

toxicity