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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 (Constant Temperature Hot Water Machine Swimming Pool Heat Pump,Light Weight Outdoor Garden Restaurant Rattan Wicker Chiavari Wedding Dining Chair (BC-08029)). As a result, several chemical methods have been applied to control P internal loading worldwide (Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material;Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb;LDPE Plastic Garbage Bags for Construction Wastes). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Factory Fluorescent Neon Powder Pigments, Cosmetic Fluorescent Pigment Powder Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (6 Position Slide Switch Manufacturers Cheap Price),1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve. 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 (Fast Building Luxury Mobile Modular Container House Material Living Container Buildings;Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time;Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice). However alum may result in high concentration of residual Al and is strongly affected by temperature (Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt) 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 (Indoor Game Sports Folding Moving Function Blue Color Top Table Tennis Table for Sales). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project;Wholesale Sport Wear Mens Gym Running Polyester T Shirt;Compatible Physio Control 11996-000033 NIBP Hose;Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly;Promotional Advertising Campaign PP Cheap Custom Logo Printed Mini Election Plastic Hand Fan;Custom PVC Shrink Capsules for Liquid Bottle;Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring).Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp(Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench;m.kt-eyewear.com;Fashion Double Striped Non-Slip Entrance Mat) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow), and it has been suggested as a lake restoration measure.
Coagulation-Osyea 2019 Outdoor Power Solar Garden LED Street Lamp(DC Colorful Battery Operated Small Hand Fan for Outdoor Use) and also by water chemistry (pH and alkalinity) (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve). 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 (High Quality Fashion Cheap Woven Polyester Petersham Hat Ribbon). At pH of 6.0-7.Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs(TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use,Wholesale Comfortable Men′s Winter Leather Snow Boots). Algae also can affect coagulation due to characteristics such as morphology, motility,Stainless Steel Handrail Long Bar Holders for 12mm Pipe(Promotion Cheap Woven Wristbands Event RFID Woven Wristband,Non Woven Wheel for Stainless Steel Polishing and Grinding,Hdmi Extender Over Cat5e/6).
In the tropical semi-Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator-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 Factory Sale Waste Logs Drum Wood Chipper. 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
Take Away Custom Logo Printing Snack Paper Pizza Box Packing, 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(Shenzhen Customized Metal Stamping Parts Fabrication Service) and concentrations of total phosphorus (Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110);Clamptek Hydraulic Speed Control Valve CZL (Low Pressure)) 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 (PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble). 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). UV254CNC Machining Milling Aluminum Bike Components(DOM), mainly as humic substances (China New Technology Swimming Pool Heat Pump (MDY50D)).
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.)JIS G3441 Machining and Structure Alloy Steel Pipe, 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 toSancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Caseas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Omd 925 Sterling Silver Antique Ring for Women Men).250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps-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 (High Quality Galvanized Pan Head Self Drilling Screw). 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 UV254Micropile Tube as Umbrella for Tunnel Portal Od73mm Wt6mm, Steel Pipe%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Automatic Wood Machined).
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(Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw). 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 (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes). 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,Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill, 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 (Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser;Jumbo Drilling Rig with Three Arms (HFG-33J);1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale;www.aiwautoseat.com). However,Portable Marking Equipment System Laser Wire Marking Machine Price.
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,3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten, Kitchen Utensils, Dutch Oven.200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter, 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 (2017 Cheap China Pistol Safe Security Gun Safe Lock). In the maximal PAC performance pH was found to be around the neutral (Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer;Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle) which determines the coagulation performance (1.5inch 1.8inch 2inch Drilling Mf Rods for Bench Drilling). 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 (Siboasi Best Selling Badminton Shuttlecock Feeder Machine).
Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe, charge and density, factors that influence directly in flock sedimentation.Thermal Transfer Waterproof Tearproof Matt Silver Pet Label(ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts; medical disposable clothes). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). Extracellular and surface-SMD P4 Outdoor Full Color Rental HD LED Display(Chain Link Mesh Factory OEM/ODM Product,Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Welding Parts), which can be one important cause of the increase in coagulant demand in algae-rich waters (PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer).Toroidal Inductor Coils Tlc/1A-221m-00 for Speaker Use., Radio etc Use.(High-Class Sld-6121 Paper Sticker High Speed Slitting Machine), particularly humic susbtances. Humic substances are highly negatively charged (Hot Sell Wireless Headphone Bluetooth Headset Hbq I7 Earphone), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer). Maximal UV254removal was observed to be found around pH 6.0 (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Smooth Surface Black HDPE Sheets for Wastewater Treatment.
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