Introduction to Environmental Engineering

Lecture 14Water Quality Continued

Chapter 8

Solids The separation of solids is one of

the primary objectives of wastewater treatment

Solid Anything other than a liquid or gas Anything remaining after evaporation at

103 C

Solids Total Solids

TS = total solids, mg/L Wds = weight of dish plus the dry solids,

mg Wd = weight of clean dish, mg V = volume of sample, L

V

WWTS dds

Solids Total Solids = dissolved solids + suspended

solids Volatile Solids = solids burned away @ 550 –

600 C FS = Fixed Solids = remaining ash from

burning @ 550 – 600 C

used is p.higher tema except MLSSas Same

conc. microbefor surrogatesolids suspended volatile VSS

FS- TSVS

g solids, unburned plus dish ofweight W

10V

WWFS

du

6ddu

Nitrogen Remember, building blocks of life

Carbohydrates, Protein, Fatty Acids, Nucleic Acids

Nitrogen is a major component of Amino Acids, which are the building blocks of protein

NH3 is an intermediate in biological metabolism Organic nitrogen and NH3 indicate recent

pollution – Kjeldahl Nitrogen test Nitrite and Nitrate indicate pollution some time

ago Both are measured colorimetrically

Bacteriological Measurements Microbiology – study of organisms that

can not be seen with the naked eye Recall, before the late 1800’s no one knew

that they existed. Louis Pasteur Range in size from 1 mm to 10-5 mm From an environmental standpoint they are

important in every compartment, Air, Water and Soil

Most of the organic carbon available for life is in the form of microbes

Bacteriological Measurements It is really their world, from a

population standpoint 1 gram of rich soil contains:

2.5 billion bacteria 0.5 million fungi 50,000 algae 30,000 protozoa

Bacteriological Measurements An Environmental Engineer needs

to have a knowledge of microbes to remove them in water treatment

(filtration and chlorination) to support them in wastewater treatment

(carbon, nitrogen and phosphorus removal from waste)

Bacteriological Measurements Only a small fraction cause disease

Pathogens Typhoid and cholera killed millions

around the turn of the century These two waterborne diseases drove

technology advancement Today, Salmonella, Shigella, Hepatitis,

Entamoeba, Giardia, Cryptosporidium are the main U.S. concerns

Bacteriological Measurements Epidemiology

The connection between pathogens in water and human disease was made by Dr. John Snow

Father of Epidemiology Determined that a Cholera outbreak was

from water downstream of London Removed the water pump, ending the

outbreak

Bacteriological Measurements Indicator Organisms

Coliforms – group of microbes used to show contamination of a source

Qualities of a good indicator organism1. Inhabits the digestive tracts of warm-blooded

animals2. Plentiful3. Easily detected4. Harmless5. Survive longer than most pathogens

Bacteriological Measurements Principal Methods of Measurement

Filter Count Coliforms captured on a filter Filter placed in agar Colonies grown and counted

MPN Test Diluted samples placed in broth Gas production indicates fermentation Count the positive reactions, statistics

Assessing Water Quality Standard Methods for the Examination of

Water Quality (Standard Methods) Quantitative Measurement Techniques of

everything that may be in water Drinking Water Standards

EPA – Primary and Secondary Standards MCL – Maximum Contaminant Level

Wastewater Effluent Standards NPDES Permit – National Pollution Discharge

Elimination System Surface Water Quality Standards

A E levels