References

Environmental and Workplace Health. (2009, March 19). Retrieved January 10, 2015, from http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/silver-argent/index-eng.php

How Is Lake Water Turned Into Drinking Water? (n.d.). Retrieved January 11, 2015, from http://www1.toronto.ca/city_of_toronto/toronto_water/files/pdf/water_treatment_process.pdf

R. L. Clark Water Treatment Plant – Water Treatment – Drinking Water | City of Toronto. (2014, January 1). Retrieved January 11, 2015, from http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=d46409f8e0c7f310VgnVCM10000071d60f89RCRD

Silver in Drinking-Water. (n.d.). Retrieved January 10, 2015, from http://www.who.int/water_sanitation_health/dwq/chemicals/silver.pdf

Silver ore_英文版. (n.d.). Retrieved January 14, 2015, from http://www.baxvilleminerals.com/templates/en/second_49_248.html

State Government of Victoria. (2012, July 27). Retrieved January 11, 2015, from http://www.epa.vic.gov.au/your-environment/water/protecting-victorias-waters/point-and-nonpoint-sources-of-water-pollution

Where Does The Water from Your Toilet Go? (n.d.). Retrieved January 11, 2015, from http://www1.toronto.ca/city_of_toronto/toronto_water/files/pdf/wastewater_poster.pdf

Water Treatment in North York

Lake Water Treatment:
A treatment plant collects raw water from lake ontario via intake pipes. It first travels through several screens to remove debris, pre-chlorination stage begins where chlorine is added to kill off all microorganisms. Alum is added to clump together small particles. The clumps then drop out of the pre chlorinated water after it is brought into a settling basin. The water then goes through layers of fine sand, gravel, and carbon(activated carbon). These are used to remove any finer remaining clumps of particles,silt, and algae. This water then goes into storage where safe levels of chlorine are added to kill any remaining harmful micro-organisms, excess chlorine is removed with sulfur dioxide. Finally, ammonia is added to combine with the chlorine which remains to stabilize it and keep the water safe. It is regularly tested before being transferred to reservoirs and pumping stations, where it then goes into our schools and homes for us to use. (‘How is Lake Water Turned Into Drinking Water?’, n.d)

(‘How is Lake Water Turned Into Drinking Water?’, n.d)

Wastewater Treatment:
Wastewater is the water that goes down our sinks and drains after we use them (e.g dishwashing, washing machine, excreting waste, etc. I starts off by being sent through bar screens which remove large debris like bottles, branches, while allowing gravel, sand, and other heavier materials to settle to the bottom of a tank. This is then brought to a primary settling tank where it is held for a couple of hours to allow particles to settle to the bottom of the basin. Oxygen is provided for microorganisms to grow, afterward eating organics in the water. This mixture is then sent to something called a clarifier, which is a basin where the solids are allowed to settle to the bottom. Finally, chlorine is added to kill off pathogens before being cycled back into lake ontario. All the waste from the previous basins and tanks, such as the gravel and solids from the purifier, are sent to the digester where they have their organic material turned to methane via micro-organisms. Any remaining biosolids can now be sent to landfill, incinerated, or be turn back into fertilizer.

(‘Where Does Water From The Toilet Go?’, n.d)

Water Treatment Plant:
R. L. Clark Water Treatment Plant is the closest provider for North York. One of four water treatment plants, it takes raw water from Lake Ontario, then cleans, disinfects and converts it into safe drinking water for the City. It is located at the foot of 23rd Street in south Etobicoke in an area known as Long Branch. (“R. L. Clark Water Treatment Plant – Water Treatment – Drinking Water | City of Toronto”, 2014)

(“R. L. Clark Water Treatment Plant – Water Treatment – Drinking Water | City of Toronto”, 2014)

 
Point and non-point source pollution:
Some examples of non-point sources are from urband development in the form of stormwater run-off, agricultural use in the form of pesticide run-off, and from forest land use causing soil erotion. Some examples of point source pollution is an oil refinery wastewater discharge outlet and combined sewer outlets.

(“State Government of Victoria”, 2012)

Our Contaminant Silver

There is no MAC for silver according to Health Canada. Silver occurs in nature in elemental form and in ores such as argentite (Ag2S), horn silver (AgCl), proustite (Ag3AsS3), and pyrargyrite (Ag3SbS3). Silver is commonly associated with lead and zinc sulphide ores. In Canada, most silver (about 70 percent) is produced as a by-product of base-metal production, and about 30 percent is obtained from silver ores. sometime people throw garbage containing garbage along with silver such as batteries, cell phones, etc. The silver mixes into the groundwater and sediments due to erosion and sometimes the silver stays on the surface of the soil. Silver stays in the water and upon consumption, a low percent of the silver is absorbed and the rest is excreted in a short time. Silver may be absorbed via the gastrointestinal tract, lungs, mucous membranes, and skin lesions. (“Environmental and Workplace Health”, 2009)

(“silver ore_英文版”, n.d)

Silver doesn’t have a huge impact towards the ecosystem because it is not a dietary requirement for organisms. It may even be lethal to bacteria, which might disturb the food chain with bacteria involved but it doesn’t have a huge impact, and it inhibits fungi reproduction. The estimated acute lethal dose of silver nitrate is at least 10 g. The only known clinical picture of chronic silver intoxication is that of argyria, a condition in which silver is deposited on skin and hair, and in various organs following occupational or iatrogenic exposure to metallic silver and its compounds, or the misuse of silver preparations. Pigmentation of the eye is considered the first sign of generalized argyria. (“Silver in Drinking-Water”, 2014)

Filter Design

The filter is a funnel that has 2 main inner layers, and a layer of coffee paper between them, on the bottom, and on top. The two main layers are sand and cotton. Cotton is has many fine fibers so it can filter out many solids, however it’s downside is that it absorbs a large volume of liquid. The sand filters out bigger debris and the coffee paper is made to ensure that all the materials stay apart, inside the funnel, and do not make a mess.

A labeled outline of the filter used to filter out the ions.

In one trial road salt was used in the filter which is sodium chloride. We thought that the roud salt would furthur replace any remaining silver ions in the compound. After the first trial however, we noticed that the water seemed very unclean and what used to be transparent was now opaque. It was thought of as general consenses among the experimentalists that the road salt was contaminating the water further. After several trials without the road salt, we continued to observe the opaque filtering and were unsure of any precipitates present. The conclusion still is that the ion present in water is indeed silver because even though a precipitate was not observed in the opaque water, it was still observed after acetate was added to the pre-filtered water.

Contamination Test

We added 10 drops of Acetate (H2C3O2) to a 10ml water solution containing either silver or lead ions. We discovered that there was a precipitate, thus there were silver ions present in the solution. We filtered out the silver and we now added Hydrochloric Acid (HCL) to the new liquid, which would filter out any lead ions, if present. There was no precipitate, meaning the original solution contained only silver ions.

Flow chart finding out which ion was present.