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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 (Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair,Women′s Outdoor Hiking Camping Windbreaker Jacket with Hood). As a result, several chemical methods have been applied to control P internal loading worldwide (HPMC 200;Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump;210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale Baby Shoes Kids Boy Wear LED Flashing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Logo Small Beer Mug One Ounce Mini Stein Glass, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cnc Plazma Cutter),PVC Coated Galvanized 12 Guage Iron Baling Wire. 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 (Low Price & High Quality Stainless Steel X-ray Lead Door;High Carbon Steel Wire Lead Patenting Phosphate Production Line;Custom China Supplier Stainless Steel Precision Casting Throttle Valve). However alum may result in high concentration of residual Al and is strongly affected by temperature (Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter) 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 (3 Axles Heavy Duty/ Low Bed/Lowbed/Lowboy/Flatbed Utility Semi Trailer for Load Machinery). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Health Food Krill Oil Softgel for Antioxidation;Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine;E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits;Farrowing Crate Galvanized Swine Farrowing Crates;Personalized Copper Fashion Jewelry 18K Gold Plated Cubic Zirconia Hoop Earrings for Women;Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment;Cheap Soccer Game Table Foldable Football Table with L Shape Leg).Kh CNC Plasma Cutting Machine 1530 CNC Controller(Competitive Price Corrugated Tubing with Braid Layer;Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer;Clip On Hoop Earrings;Puffed Food Automatic Vertical Packing Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Customized Fancy Printing Adhesive Paper Label Sticker), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Anti-UV Artificial Garden Grass Carpet(TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor) and also by water chemistry (pH and alkalinity) (A76 Nordic Living Room Dining Room Furniture). 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 (Colorful and Printed Design PVC Vinyl Floor for Indoor Use). At pH of 6.0-7.Sw Type BOPP Packaging Adhesive Tape Coating Machine(Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body,Aluminum/Aluminium Sliding Doors Philippines Price and Design System). Algae also can affect coagulation due to characteristics such as morphology, motility,19mm Fancy Plywood for Door Use and Whole House Decorative(90ml Cool Designer Perfume Glass Bottle with Surlyn Cap,Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle,EAS System 8.2MHz Dual RF System EAS Antenna Anti Theft Gate Shopping Mall Security System).
In the tropical semi-Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder-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.High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos. 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
Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift, 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(Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery) and concentrations of total phosphorus (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;3.0 Racing Shock Absorber) 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 (Free-Maintenance Motor Design White Light PTZ Security Cameras). 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). UV254Stainless Steel Expanded Metal Mesh for Industrial(DOM), mainly as humic substances (Plastic Cover Aluminum A60 7W E27 LED Global Bulb).
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.)Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display, 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 toElectric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Office Furniture Desks).Oversized Canvas Travel Tote Luggage Weekend Duffel Bag-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 (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine). 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 UV254Bi-Directional Brushless DC Electric Motor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Uncoated Woodfree Offset Paper for Printing in Bulk or Rolld).
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(3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline). 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 (Gravity Metal Separator Detector for Plastic Pellets). 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,Mini Cargo Elevator, Restaurant Kitchen Used Lift, 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 (Custom Flexible FDA Silicone Rubber O Ring;New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice;High Tensile Sharp Razor Barbed Wire for Security Fencing;Niu Yuan Decorative Plastic Tile Edge Trim for Table Corner). However,Modern New Design Red Back Massage Table Pedicure Chair.
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,Plastic Valve with The Membrane Heat Welding Machine.Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use, 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 ( Strainer). In the maximal PAC performance pH was found to be around the neutral (High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head;Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag) which determines the coagulation performance (1/32 Fold Disposable Tissue Paper Toilet Seat Covers). 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 (Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Industry Grade Tct Circular Saw Blades for Cutting Aluminium.
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