Lecture 16: Wastewater and Bioremediation Flashcards
How does increased pollution increase biological oxygen demand?
- Increased pollution overloads systems with tons of nutrients –> causes a boost in algae
- As the algae die, there is spike of sapotrophic microbes (decomposers)
- High rate of decomposition results in increased BOD
What are the steps of wastewater treatment?
- 1º treatment: physical removal of solids from influent (saw sewage)
- Screening, skimmers, settling - 2º treatment: microbial action under oxic conditions
- Bacteria are settled or eaten by ciliates, Bdellovibrio
- Viruses are adsorbed - 3º treatment: mostly chemical
What are the consequences of low nutrient levels in a wastewater treatment facility?
Nutrient deficiency leads to bacterial polysaccharide slime instead of new cell mass
- Causes bulking, foaming
- Stops wastewater treatment
- Clogs outfall
How do abiotic factor affect activated sludge?
Abiotic factors like nutrient availability, pH, and temp will effect sludge settling rate, compaction, foaming, etc.
- Low nutrients and pH usually results in foamy, slow settling, less compact sludge
What are the main characteristics of sludge and who are the main players?
Sludge: solids that accumulate in sewage treatment plants
- Active waste biomass resulting from the series of treatments so far
- Good sludge quality: plant selects for bacteria that settle well and treat water to the desired parameters
- Main players:
4% Protozoa
1% Metazoa
95% Bacteria
What are the role and characteristics of filamentous bacteria in wastewater treatment facilities?
- Filamentous bulking
- Often a settling “anchor” for flocs.
- Diffuse out but do not settle
- Can have super firm flocs and will interfere with compaction
- Can indicate low pH in wastewater
List some important protozoans.
- Stalked ciliates
- Free-living ciliates
- Flagellates
- Amoebae
What are the fungal indications of wastewater conditions?
If present with high numbers of Thiothrix, can indicate septic conditions in previous steps
What are the metazoan indications in older sludge?
Abundance indicates older sludge
- Probably time to reinoculate the sludge because the metazoans have eaten everything already
Who would you find/not find in anaerobic wastewater treatment?
- Find: fermenters, acetogens, methanogens, SRBs
- Not find: aerobic bacteria?
What is the purpose of tertiary treatment?
- Remove toxins/heavy metals
- Remove NH3
- Precipitation of phosphate
- Disinfection
What is a xenobiotic, and where do they come from?
Organic compounds not naturally degraded by microbial enzymes not naturally produced or expected to be present within the organism
- Common sites: oil spills, leaks, pesticides (agriculture)
Define bioaccumulation.
When toxins don’t leave an organism and collect in their tissues
Give examples of halocarbons.
- Polychlorinated biphenyls (PCBs)
- DDT
- Haloalkyl propellants
- Freon, chlorofluorocarbons (CFC’s)
- Haloalkyl solvents
- Chloroform, carbon tetrachloride
- Haloaromatic solvents & preservatives
- Chlorobenzene, Chlorophenols
What does DDT do?
- Insecticide used to combat several insect-borne diseases
- Harm the environment???
