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Methods in Ecotoxicology

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Val May

on 12 September 2012

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Transcript of Methods in Ecotoxicology

Group Presentation Methods in Ecotoxicology Lafleche Landfill
Moose Creek, Ontario

~200 acres
Annual treatment: 153, 000m3 of leachate
Surrounding land use:
Agricultural (crop farms)
Sod production

Several waste management facilities:
Leachate treatment
Compost facility
Household waste landfill Site Characteristics Primary Treatment Leachate is pumped into two aeration ponds lined with compressed clay
Aeration initiates an aerobic process which increases dissolved oxygen and decreases ammonia in the leachate
This step works to reduce total ammonia from ~150mg/L to 40mg/L or less Secondary Treatment Ammonia, Nitrite & Nitrate Tertiary Treatment Nitrite & Nitrate Nitrate No nitrate was detected in raw samples
1°, 2° and 3° treatment levels all had similarly high levels of nitrate
High amounts of ammonia from raw leachate is converted into nitrate and nitrite
DS contained higher levels of nitrate than US
UP contains less nitrate, possibly due to more of it being in the form of ammonia
3° leachate is released DS which has high nitrates, thus DS would contain more nitrates than UP Nitrite No nitrite was detected in the raw leachate (high ammonia levels present here)
Nitrite increased significantly in the 2° leachate
This is likely due to the active population of organisms in the RBCs which convert ammonia into nitrates & nitrites Method:
Ammonia, nitrate & nitrite were tested using a freshwater water test kit
Samples were agitated, and appropriate number of test drops were added to a 5mL sample
After 5 minutes, results were established by comparing the sample against a colour chart Ammonia Specific Conductivity, pH & Temperature Primary leachate is piped to the secondary treatment facility
Chemical treatment:
Caustic soda and sulfuric acid to make it pH balanced for optimal microbial activity, alum for metal complexing
Microbial treatment:
Rotating Biological Contactors (RBCs) remove organic carbon, suspended solids and phosphorus, and convert NH3 to NO2- and NO3 Leachate goes through a filtration treatment process using a 20 module Pall Membrane Microfiltration System
Modules have a pore size of 0.1um
Total filtration area of this system is 1000m2
This filtration process lowers
Suspended solids
Microbial pathogens (bacteria)
Iron & manganese (oxidized)
Arsenic & organics pH Method: Sp. Conductivity Results “Of the contaminants that may be found in drinking water, those present in human and animal feces pose the greatest danger to public health.” Health Canada, 2009 Specific conductivity and temperature were measured using a model YSI-85 DO, Conductivity, Temperature & Salinity meter
The meter was calibrated, inserted into the sample and values were read and recorded
pH was measured using a pHTestr 30 pH meter Purpose : Methods : E. coli test Indicator of recent fecal contamination
If absent other pathogenic organisms are probably absent Membrane filtration.
Samples collected in bottles
Sodium thiosulphate neutralizes the chlorine.
Bacteria stay on the 0.45 micron filter.
Incubation 24h at 35°C
Bacterial counts to obtain CFU (colony forming units) Temperature Error bars demonstrate a possible contamination in the raw leachate and tertiary effluent
Aeration of the primary leachate decreases the amount of ammonia present and increases the liquids biological activity.
Biofilm of the Rotating Biological Contactor could poromote E.coli growth. E.coli could have a beneficial role in the bacteria matrix.
No contamination of the tertiary leachate. Bacteria size of 0.5 micron vs 0.1 micron pore
Contamination upstream and downstream could be due to all the agricultural activity(fetilizers, animal, etc..) surrounding the ditch, stagnation or it's high concentration.
Correlation with Ammonia Results: • Absence of E. coli in the raw leachate and tertiary effluent
• High quantity observed in secondary, upstream and downstream waters No significant difference in temperature among samples was determined Conclusion and interpretations: Specific conductivity is the measure
of the water's ability to conduct
electricity; ionic activity.
Specific conductivity is directly
related to hardness.
Very significant correlation with
an R^2 of 0.919. Mg2+ and Ca2+ affect both the hardness and the specific conductivity.
CO2 is supersaturated in Raw lechate due to the decomposition of garbage
High HCO3 levels decrease upon aeration in the primary level, decreasing the amounts of dissolved carbonate ions. Maxim Robert, Husam Saleh,
Regine Lam and Valerie May a a a a b b b Total ammonia concentration decreased significantly as Raw leachate was processed
Un-ionized ammonia was highest in primary treatment
Un-ionized ammonia is driven by pH and temperature
Upstream levels higher than downstream
Total ammonia is low in secondary and tertiary treatment
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