21Mar

Introduction 

Wastewater is defined as any water that has been negatively affected in quality by humans. Wastewater is comprised of liquid and solid waste that is discharged from domestic residences, commercial properties, industrial plants, and agriculture facilities or land. Wastewater contains a wide range of contaminants at various concentrations. 

Characteristics of Wastewater 
The three main characteristics of wastewater are classified below. 

1. Physical Characteristics 
· Turbidity 
· Color 
· Odor 
· Total solids 
· Temperature 

2. Chemical Characteristics due to Chemical Impurities 
· Chemical Oxygen Demand (COD) 
· Total Organic Carbon (TOC) 
· Nitrogen 
· Phosphorus 
· Chlorides 
· Sulfates 
· Alkalinity 
· pH 
· Heavy Metals 
· Trace Elements 
· Priority Pollutants 

3. Biological Characteristics due to Contaminants 
· Biochemical Oxygen Demand (BOD) 
· Oxygen required for nitrification 
· Microbial population 

Wastewater characteristics, as well as water treatment processes, are important for environmental engineers to understand. Our FE Environmental exam review course thoroughly reviews the characteristics of wastewater. 

Physical Characteristics of Wastewater 
· Color - Fresh sewage is normally brown and yellowish in color but over time becomes black in color. 
· Odor – Wastewater that includes sewage typically develops a strong odor. 
· Temperature - Due to more biological activity, wastewater will have a higher temperature. 
· Turbidity - Due to suspended solids in wastewater, wastewater will have a higher turbidity, or cloudiness. 

Chemical Characteristics of Wastewater 
Wastewater contains different chemicals in various forms as mentioned below. 
· Chemical Oxygen Demand (COD) - COD is a measure of organic materials in wastewater in terms of the oxygen required to oxidize the organic materials. 
· Total Organic Carbon (TOC) - TOC is a measure of carbon within organic materials. 
· Nitrogen - Organic nitrogen is the amount of nitrogen present in organic compounds. 
· Phosphorous - Organic phosphorous (in protein) and inorganic phosphorous (phosphates, PO4- ) 
· Chlorides (Cl-) 
· Sulfates (SO4-2) 
· Heavy metals 
  1. Mercury (Hg) 
  2. Arsenic (As) 
  3. Lead (Pb) 
  4. Zinc (Zn) 
  5. Cadmium (Cd) 
  6. Copper (Cu) 
  7. Nickel (Ni) 
  8. Chromium (Cr) 
  9. Silver (Ag) 

Analyzing the physical and chemical characteristics of wastewater plays a critical role in the wastewater treatment process. Our FE Environmental review course greatly emphasizes wastewater treatment methods based on the physical and chemical characteristics of the water. 

Biological Characteristics of Wastewater 
· Biochemical Oxygen Demand (BOD) - BOD is the amount of oxygen needed to stabilize organic matter using microorganisms. 
· Nitrogenous Oxygen Demand (NOD) - NOD is the amount of oxygen needed to convert organic and ammonia nitrogen into nitrates by nitrifying bacteria. 
· Microbial life in wastewater - Wastewater contains the following microbes: 
  1.  Bacteria 
  2.  Protozoa 
  3.  Fungi 
  4.  Viruses 
  5.  Algae 
  6.  Rotifers 
  7. Nematodes 
· Oil and Grease - Oil and grease originate from food waste and petroleum products. The amount of oil and grease in raw wastewater varies from 10 to 109 mg/L. 

It is important that those who are striving to obtain their FE certification fully understand how to regulate the biological characteristics of wastewater through appropriate treatment methods.