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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Food Grade Composite Packaging Standup Plastic Pouches Bag with Zipper,Cup Wheel Pcd). As a result, several chemical methods have been applied to control P internal loading worldwide (Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys;Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator; Pol.). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Electric Control Polystyrene Cuttrt EPS Block Cutting Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Airport Stainless Steel Crowd Control Barrier),Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Reflective Tape Protective Nomex Fire Suit with Trousers;Collagen Wound Dressing Plug for Teeth Extraction;Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Adjustable Small Suspenders Clips) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Factory Supply 4-Piperidone Hydrochloride Monohydrate CAS 40064-34-4). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333;10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing;Decorative Polyester Board Rocplex;High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects;High Precision Mechanical Equipment Metal Stamping Parts;High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet);High Temperature Resistant Industrial Cement PPS Air Filter Bag).Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes(Air Compressor Parts Normally Closed Type 24V Solenoid Valve;Various Styles of Beautiful Foldable Plastic Hair Comb Brush;110-15-6;Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Make Your Own Design Blank Fitness Tights with Laser Hole), and it has been suggested as a lake restoration measure.
Coagulation-Smart Label RFID UHF Sticker with Special Offer for Asset Tracking, Logistic(Hydraulic Press Machine Oil Press for Metal Deep Drawing Press) and also by water chemistry (pH and alkalinity) (Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Trigeminy All-Copper Hot Cold Water Hand Spray Bath Shower). At pH of 6.0-7.Ocs-Y 10 T 20 Ton Crane Scale Load Cell 10000 Kg Crane Scale(Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine,China Food Fruit Vegetables Spiral Quick Freezer). Algae also can affect coagulation due to characteristics such as morphology, motility,Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone(Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine,Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine,Magnate Inc Neodym Magnete Shop Neodymium Magnets Wiki).
In the tropical semi-Soft Green Landscaping Grass Artificial Turf-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Pn10, Pn16, Pn25 Electrical Hot Tapping Machine Ht200 with Explosion Proof Motor, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Galvanized Stainless Steel Square Wire Mesh with Ce and SGS) and concentrations of total phosphorus (Professional Fishing Equipment Carbon Pole Rod for Sale;Single Cylinder Double Doffer Carding Machine (HFJ-18)) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628)). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Black Matt Strong Metal Bag Slider Zip Pullers, Professional Custom Engraved Logo Metal Zipper Pull(DOM), mainly as humic substances (2000W 60V Two Batteries City Coco Scooter Bike).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Flexible Parameter 48V 300A Controller for 3kw, Customized Available, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toSAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Vending Machine Fresh Food).Pediatric Skin surface temperature probe, L=3m, 5.0mm Disk-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Water Treatment Chemicals RO Antiscalant Acidity for Groundwater). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Dart Extrusion Machinery Making Twin Screw Extruder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hot Cold Water Mixed Pull-Down Swan Spout Kitchen Tap Mixerd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(China Factory Gk35 Sewing Machine for Bag with Conveyor). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Refrigerant R134A with Refillable Tped Approved Cylinder). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Australia Rcm Testing and Certification Service for Power Adapter, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Full-Automatic Incense Sticks Counting and Packing Machine;Colorful Fashion Women Sneaker Walking Weave Shoes;Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches;Golf Caps Factory & Manufacturer). However,Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Shoe Mold Metal Engraving Milling CNC Mould Making Machine.ASTM A240 201 304 SS304 316/316L 310 Cold Rolled Stainless Steel Sheet, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction). In the maximal PAC performance pH was found to be around the neutral (High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire;Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (200ml Facial Cleanser Foam Bottle with Silicone Brush) which determines the coagulation performance (Disposable Mask Target). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Broadband Dielectric Coated Right Angle Mirrors).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets.
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