Characteristics of wastewater flowstreams and treatment options

Question 1

Which organics are found in WW and how are they measured?

Answer 1

 Carbohydrates, fat/oil/grease (FOG), proteins
 Pesticides, surfactants, priority pollutants
 Volatile organic compounds
 Parameters: BOD, COD, TOC, DOC

Question 2

Which inorganics are found in WW?

Answer 2

 Alkalinity
 Chlorides
 Nutrients (N, P, K, S)
 Priority pollutants
 Heavy metals

Question 3

Which units describe solids and how are they measured?

Answer 3

 TS, total volatile solids (TVS), TSS, total fixed solids (TFS), volatile suspended soilds (VSS), fixed suspended solids (FSS), total dissolved solids (TDS), VDS, FDS, settleable solids (SS)
Measured by;
 Turbidity [NTU]
 Imhoff cone for SS
 Vacuum filtration apparatus for TSS

Question 4

Which gases are found in WW?

Answer 4

 Hydrogen sulfide H2S
 Methane
 Off-gases in biofilm/activated sludge systems, or during storage and transport of e.g. urine (for example laughing gas N20 or ammonia NH3)

Question 5

Which microorganisms are found in WW and where are they from?

Answer 5

 Bacteria, fungi, algae, protozoa, helminths, viruses
 Source: human waste
 Indicator bacteria: E.coli, total coliforms, intestinal enterococci, C. perfringens

Question 6

What are the resources and challenges with urine?

Answer 6

o Resources: Nutrients (N, P, K)
o Challenges: pharmaceuticals, pathogens

Question 7

What are the resources and challenges with dry faeces?

Answer 7

o Resources: organic matter, nutrients
o Risks: pharmaceuticals, pathogens

Question 8

How do you compost dry faeces?

Answer 8

o Composting – 1 yr storing before use in garden, 2 yr before use on vegetables that are eaten raw

Question 9

What are the resources and challenges with blackwater?

Answer 9

o Resources: energy, organic material, nutrients
o Challenges: pathogens, micropollutants (e.g. pharmaceuticals)

Question 10

What are the resources and challenges with greywater?

Answer 10

o Resources: water, heat
o Challenges:
 Microbial constituents (pathogens)
 Organics (FOG, surfactants)
 Micropollutants

Question 11

Pollutants to treat in greywater

Answer 11

o Biodegradable organics
o Indicator bacteria
o Nutrients
o FOG
o Suspended solids
o Microplastics
o Micropollutants
o Dissolved inorganics (calcium, sodium, sulfate)
o Possibly heavy metals

Question 12

What are the resources and challenges with rainwater?

Answer 12

• Rainwater
  o Resource: water
  o Challenges: Compounds from roof, pathogens, solids, colour

Question 13

What can be considered acceptable levels of BOD, turbidity and E.coli?

Answer 13

A biological oxygen demand (BOD) of less than 10 mg·L−1, a turbidity of less than 2 NTU and a non-detectable level of faecal
coliforms is likely to be acceptable worldwide