WATER QUALITY AND TREATMENT OF WATERS How polluted is the water from your home, river/creek, and sea water? Darrylynn Majied, Morningside HS and Montse Plascencia, Hamilton HS
Introduction Our main objective is to analyze the water quality of four water samples: tap water, Stone Canyon Creek (UCLA), Alamo River and Red Hill (from Salton Sea). Basic water quality of these samples is analyzed: alkalinity, hardness, nutrients, suspended solids, chloride and sulfate. Coagulation/Flocculation was used to treat a mixture of Alamo River and Red Hill samples.
Alkalinity and Hardness
Alkalinity is the water capacity to resist change in pH due to acid addition. It protects aquatic life against rapid pH changes.
Hardness is caused by divalent cation e.g., calcium and magnesium.
Hardness does not cause adverse health effect but hard water requires greater amount of soap to produce foam; it can also cause scaling in hot water pipes.
Our results show tap water has the lowest alkalinity and hardness
Alkalinity of Alamo River and Salton Sea was ~ 200 mg/L as CaCO3
Salton Sea sample has the highest hardness, ~2300 mg/L as CaCO3
Hardness experiment – EDTA titration method To determine the hardness a titration with EDTA solution must be used. When the titration begins the EDTA cancels out all the M2+, letting EBT, the indicator, free and causing the color change from burgundy to blue.
Nitrogen and Phosphorus Nitrogen species analyzed: ammonia, nitrite and nitrate. Phosphorus analyzed: ortho-Phosphate. Both nitrogen and phosphorus are nutrient that stimulates plant growth; however, excessive amount of this nutrient result in an algae bloom, which can reduce dissolved oxygen in water and adversely affect aquatic life.
Nitrate concentration was the much higher than ammonia and nitrite in all samples; an indication of pollution which occurred a while ago.
Nitrate concentration in Red Hill exceeded 10 mg/L, limit set up US EPA.
Ammonia and nitrite of all samples were less than 1 mg/L.
Unlike nitrate, Alamo River has greater phosphate concentration(~ 4.5 mg/L) than other samples.
High concentration of phosphate in Alamo River may be due to the fertilizer used by the farm land nearby.
Same as nitrate, high concentration of phosphorus would promote algae growth and affect the aquatic life.
Nitrite experiment – Colorimetric method
Suspended Solids Suspended solids have a diameter greater than 2.5 um in size. Suspended solids can float and form unpleasant scum layers or sink and cause sediment buildup. High suspended solids can reduce aesthetic for recreational activities and visibility of waters. Turbidity is measured when the sample’s light is blocked by large amounts of silt, microorganisms, plant fibers, sawdust, wood ashes, chemicals and coal dust. In other words, any substance that makes the water cloudy will cause turbidity.
Alamo River has the highest concentration of suspended solids (~ 400 mg/L) and turbidity (~220 NTU), followed by Red Hill sample.
Treated wastewater effluent is required to have 30 mg/L of suspended solids; indicates TSS in Alamo River and Red Hills need to be treated.
Total Suspended Solids experiment – Gravimetric method Circular filter was used to contain the suspended solids from the water samples. Then they were measured to see which sample contained the most suspended solids. Creek contained the least amount of TSS with 4.25, Salton Sea contained 92.4 TSS, and Alamo River contained 397.35 TSS.
Sulfate and Chloride Both sulfate and chloride ions are monitored in waters due to their effects on the taste (chloride) and odor (sulfate) in high concentration. High concentration of sulfate ion can also cause scaling and corrosion in water pipes. Hydrogen sulfide (“rotten-eggs smell”) is released under anaerobic (no oxygen) condition.
Red Hill has the highest sulfate (2900 mg/L) and chloride (4700 mg/L) concentrations among the four samples.
The sulfate and chloride concentrations of Alamo River is 1/10 and 1/20 of those of Red Hills, respectively.
Both samples exceeded the sulfate and chloride limits set by US EPA, 250 mg/L.
Three major types of treatments: physical, chemical and biological can used to remove pollutants from waters.
We used a chemical treatment (coagulation and flocculation) for this study.
Coagulation and flocculation is a process that allow particles to react and grow in size; bigger floc will form due to an addition of a coagulant (e.g. aluminum sulfate) to the water.
Aluminum sulfate (1 – 300 mg/L) was added to our samples (a mixture of Alamo River and Red Hill samples) and rapid mixed at 300 rpm for 1 min, slow mixed at 30 rpm for 15 min. After 30 min. settling, the turbidity of the water was measured.
Coagulation / Flocculation Sample of Alamo River and Red Hill combined was placed into six large beakers, then different amounts of aluminum sulfate was added . Finally the stirring began, and the attraction of the TSS initiated.
Process of TSS combining.
The end results of coagulation. Observe both beakers, which one is more clear. Therefore coagulation is a method of treatment, causing the water to be more pure.
Conclusion Our results show the water quality of Alamo River and Red Hill from Salton Sea is more polluted than the tap water and Stone Canyon Creek. Treatment is urgently needed to improve the water quality of these two water bodies.
Acknowledgements UCLA Henry Samueli School of Engineering and Applied Science UCLA Center for Excellence in Engineering Diversity (CEED) Staff Howard Hughes Medical Institute (HHMI) Dr. Sim Lin Lau, Civil and Environmental Engineering Department