14 environmental tox of complex effluents Flashcards
what is the outline of this lecture?
-what are complex effluents?
-why are they a problem?
-how do we monitor/assess their impact?
-regulations for effluent discharge?
what are complex effluents?
-effluent is water mixed with waste matter (liquid waste discharge)
-contain complex mixtures of compounds: both natural and man-made
-exert complex effects on an organism (often very site specific)
what are the sources of effluents?
domestic
-municipal wastewater (sewage)
industry
-metal mines (alot in canada)
-pulp and paper mills
-textile mills
-potato processing plants
-meat and poultry products plants
-petroleum refineries
what is municipal wastewater? why is it needed?
what: liquid wastes from sewer system and municipal wastewater treatment plants (MWTPs)
why
-volume: MWTP discharges=5.7 billion m^3 annually in canada
-pollution: organic waste, suspended solids, nutrients, pathogens, 100s chemicals (even advanced treatment have 100s of chemicals)
what are the impacts of municipal wastewater on aquatic environment?
-destruction of habitat from sedimentation (contains suspended solids and eventually precipitate out of water column)
chemical contaminants
-estimated 60,000 man-made chemicals in use, most enter aquatic environment
-pharmaceuticals are a huge issue
what are the human health impacts of municipal wastewater?
-recreational use=bacterial contamination
-fishing: fish contain bacterial contamination, biotoxins, metal accumulation, organics
-drinking water= bacterial, metal, and/or nitrate contamination, organics, drugs
what happened in North Battleford in spring 2001?
waterborne cryptosporidiosis outbreak
-cryptosporidium parvum is a protozoan parasite that has been a recognized human pathogen since 1976
-very common in raw sewage
-health effects include diarrhea, headaches and stomach aches
-5800 to 7100 persons in the Battlefords developed gastroenteritis as a result of the outbreak
how did the outbreak in North Battleford occur?
surface and well water used as drinking water
-surface treatment plant was shut down for a week, the workers realized disinfectants were working properly, so all drinking water got contaminated
what are the sources of municipal/urban wastewater?
municipal/urban wastewater is a term typically used to describe liquid wastes from two types of sources:
1. sanitary sewage: generated from homes, businesses, institutions and industries
2. stormwater: generated from rain or melting snow that drains off rooftops, lawns, parking lots, roads and other urban surfaces
who owns most wastewater systems?
in Canada, most wastewater systems are owned and operated by municipalities
-all levels of government share the responsibility for managing the collection, treatment and release of wastewater effluent
-federal Govt. is responsible for managing the risks posed by substances listed under the Canadian Environmental Protection Act, 1999
what are the steps of the treatment process?
- preliminary=screening
-clarifier=sedimentation tank (suspended solids will be precipitated out) - primary=sedimentation
-clarifier=sedimentation tank (suspended solids will be precipitated out) - secondary=biological
-enrich effluent water with bacterial load and vigorously pump water (breaks down organic waste) - tertiary=removal of bacteria, suspended solids, specific toxic compounds or nutrients
-includes disinfecting processes, specific filtering and adsorption techniques
what is the table of effluent quality from various sewage plant treatment processes?
not able to completely eliminate
-numbers go down so they significantly increase quality of effluent
increased BOD=poor quality effluent
what are the levels of treatment in each province?
water is priceless in SK so we cannot risk to contaminate freshwater
what needs to be done to municipal waste-water before it can be released into the environment?
obtain approval from provincial government
WET (whole effluent toxicity)
-toxicity tests of undiluted effluent required to permit release of effluents that have potential to cause deleterious effects on receiving aquatic environment
what are the WET tests?
what are the WSER?
canadian wastewater systems effluent regulations (WSER)
-average BOD in the effluent: less than or equal to 25 mg/L
-average concentration of suspended solids (SS) in the effluent: less than or equal to 25 mg/L
-average concentration of total residual chlorine in the effluent: less than or equal to 0.02 mg/L
-maximum concentration of un-ionized ammonia in the effluent: less than 1.25 mg/L
-the effluent must also not be acutely lethal based on the test methods prescribed in the regulations
what is the summary of reported acute lethality tests results by province?
what is the assessment and monitoring process?
what is TRE?
TRE= toxicity reduction evaluation
-identify causative agent
-isolate source of toxicity
-evaluate effectiveness of removal
-confirm reduction in effluent toxicity
prevention or cure method:
-achieve compliance with WSER limit (cute)
-evaluate effluent toxicity before it becomes a problem (prevention i.e. continuous monitoring technique)
what is the status of the metal mining industry?
status
-around 100 metal mines in Canada (mainly QB and ON)
-17.8% of canadian gross domestic product
-top five in world for production of nickel, zinc, cadmium, aluminum, platinum group metals, gold, molybdenum, copper, cobalt and lead
what is mining wastewater effluent? what do we want to reduce? what are the impacts?
-wastewater treatment plants (WWTP) to treat wastewater from the mine, waste rock and tailings
reduce:
I. toxic metals/chemicals
II. control pH of effluent (6-9) (use lots of acid)
III. total suspended solids (TSS)
IV. dissolved organic carbon (DOC)
impacts= metal contamination and acidification of aquatic environment (bad bc more acidic means more of metal that is bioavailable)
what are the effects of metal mine effluent?
sedimentation and turbitity
-destruction of habitat which decreases light and decreases biological productivity
acidification
-metal dissolution which leads to bioaccumulation of metals in benthos and fish
-pH<5=fish and invertebrates unable to breed
-pH<6=lethality to sensitive populations
ultimately leads to altered community structures (all sensitive species die)
what is the history of metal mining?
metal mining industry in canada since 1800’s
-1960’s: contamination a concern. Evidence of heavy metals in surrounding lakes and rivers
-1970’s: substantial effort by industry to control metal discharges
-1990’s: metal mining industry regulated under the EEM (environmental effect monitoring program)
what are the regulations of metal mining effluent (MME)?
the regulations to allow the discharge of MME into natural waters are subject to certain requirements:
-concentration of the deleterious substances (e.g. metals, TSS) in the effluent does not exceed the authorized limits (weekly)
-pH of the effluent is equal to, or greater than, 6.0 but is not greater than 9.5 (weekly)
-undiluted treated effluent is not acutely lethal (<50% mortality of rainbow trout over 96 hours) (monthly)
-EEM assessment of the receiving environment (every 3 years)
what is the EEM program used in metal mining effluent?
environment effects monitoring program
-EEM is a monitoring program conducted to identify and evaluate any effects of effluents on fish, fish habitat (benthic invertebrates), and the use of fisheries resources in the receiving water
EEM=effects on communities in the receiving environment
why focus on fish?
-to assess aquatic systems
-look at because they are higher trophic levels, get assessment of all in system (indirect or direct effects)
what is the EEM program looking for (objectives)?
-survival: most old fish= young ones aren’t surviving (and vice versa)
-energy use: look at ratios of gonads to body weight which is an indicator of reproductive health
-energy store: liver versus body weight is an indicator of metabolic health
-BI: healthy community=indicator of overall health
which one is better regulatory approach: municipal waste water (WET) or metal mining effluent (EEM)?
EEM is better: more robust and effective
1. WET has no requirements for testing in actual receiving environment (dont look at long-term effects)
-WET no matter how advanced, there will still be contaminants at low levels (as well as EEM)
- EEM does ecological impact assessments on actual receiving environment
-done every 3 years, we keep historical records which can help long-term and creation/changes of plants
