The Phosphate Filter: Which Type of Soil? Noah Haibach Central Catholic HS

Phosphorus Pollution Phosphorus can cause problems in the human digestive tract. It is a growth-limiting factor. Causes overgrowth in streams and ponds; can destroy aquatic ecosystems. Comes from human waste, fertilizer, detergents, and industry point sources.

Phosphorus Treatment Water treatment plants cannot efficiently remove phosphorus from water. Marshes can effectively remove the phosphorus. They prevent excess nutrients from causing overgrowth in bodies of water. Some marshes are constructed to treat water with high levels of phosphorus. Ex: Florida Everglades

Acceler8 $8 billion project currently under way. Add 6,000 acres to State’s current 36,000 acres of treatment marshes. Lower P levels to  g/L or ppb. P levels above this limit can cause imbalances in algae, plant and small animal communities. Florida Everglades

Phosphorus Absorption 1. Incorporation into Biomass a. locked away into organic compounds by plants. 2. Retention by Soil* a. physical precipitation b. chemical absorption, where P binds to Al, Fe, or Ca. Fe must be in the fully oxidized form of iron (III) oxide. * Both soil removal techniques sensitive to DO level.

Purpose In Light of Previous Experimentation Soil removed much more P from a water sample than did cattails. Soil removed about 500  g from 1 L solution in 2 days. Chemical absorption appears to be quickest method of P removal. Soil was mixture of organic & inorganic. Which type of soil (organic or inorganic) removes the most P? Do iron oxide levels affect P removal?

Hypotheses Organic soil will be richer in P, Ca, and Fe than the inorganic soil (sand). Organic soil will remove more P than sand, due to chemical absorption of P. Treatments with added iron oxide will also remove more P than treatments without.

Materials 20 clear 2-Liter pop bottles bottles distilled water Anhydrous KH 2 PO 4 Reagents for the molybdenum blue ascorbic acid method (4500-P E. method) Ocean Optics USB 2000 spectrophotometer mL test tubes w/lids 10% organic content soil Sand High-grade iron (III) oxide Graduated cylinders Automatic pipettes; micro and macro

Procedure 1.First, gather the materials needed. Then, prepare a stock solution of 100 P mg/L (ppm). Add stock solution to each of the distilled water containers, so that they have a concentration of 1 P mg/L. 2.Prepare cakes of soil. Mix 240mL soil/sand with 60mL water. If called for, add iron oxide so that iron oxide content is 4%. Freeze the cakes. 3.Follow the below diagram for setup, with 4 reps for each treatment. 4.Take 10mL samples over a period of time. 5.Prepare the reagents for the molybdenum blue ascorbic acid method, and react the samples. This colorimetric test turns them blue. 6.Determine the phosphorus content of samples, using a standard curve. 1 P ppm Soil Soil & Fe Sand Sand & Fe Control 1 P ppm SoilSand 1 P ppm SoilSand Iron Oxide 1 P ppm

Too much initial P: 5 mg/L P concentration outside of range of colorimetric test: 1 cm cuvette range of 0.15 – 1.30 P mg/L Too little soil: 120mL/treatment After 1 week, very little P absorbed Corrective Steps Lower initial P to 1 mg/L Double size of soil cake Experimental Corrections Extremely Dark Samples

Data Day 0Day 2Day 4 Control Sand Soil Sand & Fe Soil & Fe Arithmetic Standard Mean Deviation 4 replicates/treatment

Chart

Anova Results Day 4 Treatments P Values ControlSandSoilSand & FeSoil & Fe Control E E E-03 Sand E E E-04 Soil E E-03 Sand w/ Fe Soil w/ Fe Chart Observations The soil-containing samples varied from the control. The sand did not vary from the control, but the sand & Fe did vary. The sand varied from the soil. The Fe made a difference: sand varied from sand & Fe. soil varied from soil & Fe.

Conclusions Treatments with added iron oxide did remove more P than those without. Organic soil removed more P than the sand, which removed no P in comparison to the control. Sand & Iron removed more P than Organic Soil & Iron. Due to the high amount of P already present in the organic soil: Organic soil: 9 P mg/L* sand: 1 P mg/L* Dissolved oxygen levels in the soil were 4.9mg/L. DO in the control was 7mg/L; anaerobic conditions may have caused release of P from the organic soil. *Data obtained from Penn State Agricultural Analytical Services Laboratory

Accreditations Special Thanks to… Dr. Ron Ripper and Carnegie Mellon University Dr. Carrie Doonan Dr. John Stolz of Duquesne University Sources Standard Method for the Treatment of Water and Wastewater, 18 th ed. (Washington D.C.: American Public Health Association, 1992), pp & University of Florida, “Wastewater Treatment Wetlands: Applications and Treatment Efficiency,” Science Daily, “Everglades Phosphorus Limits On The Right Track, But More Is Needed”,

Sand Sand + Fe Org. soil Org. soil + Fe Control