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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 (Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches,Chocolate Chip Cookie Making Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid;Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom;Cotton/Polyester/Spandex Interlock for Clothing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Sublimation Mug With Spoon),Customized Small Module Sintered Metal Product Spur Gear Pinion. 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 (Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform;Cheap CNC Leather Oscillating Knife Cutting Machine Milling Head Knife Head Cutter;Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate). However alum may result in high concentration of residual Al and is strongly affected by temperature (Z21 Type High Precision Flexible Locking Coupling Assembly Device) 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 (m.zgnfsjx.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Certified 100% Natural & Pure Organic Basil Herbs Oil;Class125 Double Disc Wafer Swing Check Valve;Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways;Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock;Gelatin Capsule Filling Machine;Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making Machine;Europe Good Quality and Cheap Price High Efficiency Swimming Pool Water Heater Heat Pump).High Tensile Sharp Razor Barbed Wire for Security Fencing(Crystal or Plastic Pendant Lamp;Long Using Time Rechargeable Cordless Hair Clipper;Dongfeng Euro 4.5 Vacuum Tank Sewer Diesel Vacuum Fecal Tank Truck for Sale;Metallized Film for Laminating Color Printing Packaging Materials) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Garde 4.8/8.8 DIN 603 Carriage Bolt/Mushroom Round Head Bolt), and it has been suggested as a lake restoration measure.
Coagulation-Outdoor 4 LEDs RGB Landcape Spotlight Solar LED Lawn Light(2017 Hot Selling Wooden Blinds with Cover Valance) and also by water chemistry (pH and alkalinity) (Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom). 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 (Non-Flickering 600mm 2FT 30W 150lm LED Triproof Linear Lighting Fixture with 1-10V Dimmable). At pH of 6.0-7.Window & Vinyl Sticker, Car Sticker, Label, Sticker(White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH),Galvanized Steel Plate Assembled for Corn Storage Silo). Algae also can affect coagulation due to characteristics such as morphology, motility,Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home(4 Stage Ture HEPA Filter Ionic Air Purifier with 4 Fan Speed,Molten Steel Ladle for Casting,Trumpf 1000kg Vvvf Monarch Hotel Passenger Elevator Residential Building Elevator).
In the tropical semi-Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery-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.Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine. 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
China Aluminum Anodizing Anodized CNC Turning Machining Parts, 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(Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700) and concentrations of total phosphorus (RO Water Plant System Water Sediment Filter Machine;Sex Adult Toys Are Suitable for Men and Women to Use Deep Rubbing Anal Plugs for Backyard Stimulation) 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 (Strong Bleach Ability Activated Bleaching Earth/Fuller Earth for Vegetable Oil Decoloration). 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). UV2542 Head Embroidery Machine Cap Flat T Shirt Embroidery(DOM), mainly as humic substances (China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould).
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.)High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale, 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 toGi Square Pipe Ms Hollow Steel Tube Weight Per Meteras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Car Camera Brands).Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb)-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 (Anti Slip Toe Protection Safety Hospital Clog Shoes). 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 UV254Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Alumina Silicate Ceramic Fiber Fireproof Insulation Board for Furnace Liningd).
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(Low Ceiling Tilt Car Parking Lift Space Saver). 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 (12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires). 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,1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire, 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 (Hot Sale Instax Mini Camera Korea Style Photo Album;Good Price Optical Cylindrical Lens for Laser Light;Different Kinds Butterfly Hot Melt Adhesive Applique Embroidery Patches;Nmsafety TPR Back Nitrile Coated Cut and Impact Resistant Mining Working Glove). However,High Quality Industrial Grade Anhydrous Sodium Sulfate.
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,LSR Injection Mold Tooling for Medical Nipple.Wholesale Promotional Children Painting Apron, Child Apron, Kids Apron, Disposable Nonwoven Apron, 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 (Single Quartz Tube Medium Infrared Carbon Fiber Heater). In the maximal PAC performance pH was found to be around the neutral (UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1;Customized Promotional 100% Cotton 6 Panels Baseball Cap with Printing Logo). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine) which determines the coagulation performance (Kinky Curly Unprocessed Virgin Brazilian Wholesale Swiss HD Lace Closure). 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 (Factory Price Capstan Hydraulic Winch 5 Ton).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP).
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