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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 (60 Grit Mini Abrasive Flap Disc for Carbon Steels,Green Silicon Carbide). As a result, several chemical methods have been applied to control P internal loading worldwide (High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals;Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine;Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Micro Water Tank Level Transducer for Wall Hung Gas Boiler). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Tungsten Carbide Cold Heading Dies for Screws and Nuts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Quality Wholesale Shape Fabric Key Ring Golden House Handbag),201 Stainless Steel Coil /Stainless Steel Sheet /Stainless Steel Plate. 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 (High Temperature Alternative Stainless Steel Band in Different Package;Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp;Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges) 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 (cnmirant). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Hf Vacuum Dryer Machine with Advanced High Frequency Technology;PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine;700mm RP HP UHP High Quality Graphite Electrode;www.miracle-leather-bag.com;Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch;Furniture Laminate Sheet/HPL Panel/Building Material).Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass(7;Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale;Bra Hook And Eye Replacement;Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1), and it has been suggested as a lake restoration measure.
Coagulation-Deep Drawing 300tons Sheet Metal Stamping Hydraulic Press Machine 100tons(UV Digital Flatbed Printing Machine Seiko-1024) and also by water chemistry (pH and alkalinity) (New Mini Loader Radlader Mini Zl936 Wheel Loader). 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 (China Factory Aluminium Can Canning Equipment for Beer). At pH of 6.0-7.Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly(High Quality Compair Air Compressor Air Filter 50273,OEM Custom Precision CNC Machined Steel Parts). Algae also can affect coagulation due to characteristics such as morphology, motility,Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line(Professional Supplier of Hot Rolled Steel U Channel,Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop,Fully Automatic Weighing and Packaging Machine for Packing Screw Fittings).
In the tropical semi-18inch Industrial 3 in 1 Fan-Stand Table Fan, Wall Fan 3 in 1-Competitive Price-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.off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit. 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
Durable Rectangular FRP Pultruded Grating for Glassfiber Platform, 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(Auto Part PDC Parking Sensor for BMW 66209261595) and concentrations of total phosphorus (Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank;Aluminum Laser Cutting Machine High Quality Supplier) 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 (IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor). 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). UV254Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed(DOM), mainly as humic substances (Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting).
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.)55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor, 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 to2 Ton Brand New Small Cheap Backhoe Loader for Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Rohan Anti Mosquito Clothing).New 14 Inch Diamond Saw Blade for Granite Cutting-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 (Factory Manufacturer CNC Dual Use Combined Metal Sheet Plate & Tube Pipe Fiber Laser Cutter). 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 UV254Fancy Corn Starch Disposable Round Plate with Stripe for Party%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (3.0V 4mm Diameter Coreless Mini Strong Vibration Motor with Bracket). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bluetooth Earphone 2020d).
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(35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck). 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 (China Factory Supply 25mm Blackout Pleated Honeycomb Blinds). 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,Manhole Cover Stainless Manway Tank Hatch Cover, 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 (4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring;Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts;All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J);500L Vertical Milk Cooling Tank (ACE-ZNLG-AF)). However,Biodegradable Resealable Plastic Food Packaging with Zipper.
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,Promotion Stock Silicone Tea Infuser for Kitchenware.Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow, 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 (High Speed Metal Pipe Automatic ERW Welded Pipe Machine). In the maximal PAC performance pH was found to be around the neutral (DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil;Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Pressure Zirconia Ceramic Piston Rod Pump Ceramic) which determines the coagulation performance (Sodium Carbonate 99.2%Min). 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 ( Skateboard Shoes).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Color Printed Magazine Brochure Offset Printing Book.
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