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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 (630kgs Galvanized Suspended Platform,8 Stainless Steel Reusable Ice Cubes). As a result, several chemical methods have been applied to control P internal loading worldwide (Schedule 40 Stainless Steel 304L Pipe and Tube;Auto Parts Engine Cooling Air Conditioner OEM 88450-26120;New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (100W/150W/200W Industrial High Bay UFO LED for Tennis Court Lighting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Forged Cap),Hot Dipped Galvanized Steel Horse / Sheep Wire, Cheap Cattle / Field Fencing. 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 (Eeto Laser Metal Sheet Fiber CNC Laser Cutting Machine Price; Cheap Cattle / Field Fencing;Bimetal Bushing Composite Oilless Bush Sliding Bearing Bush). However alum may result in high concentration of residual Al and is strongly affected by temperature (PU Foam CNC Circular Contour Sponge Cutting Machinery/EPE Cutting Machine) 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 (Geared Hub Motor). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (HRC60 4 Flutes Corner Radius Solid Carbide Cutting Tools End Mill;Industrial Automatic High Quality PVC Fast Speed Roller Shutter;Install High Density Hardie Ceiling Tile Fiber Cement Board;Magic Mirror Facial Skin Analyzer / 3D Face Camera;Building Material Cleanroom System 100mm Rock Wool Core Sandwich Partition Board;Cement Grout Pump Grouting Machine Price Concrete Grouting Machines;Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery).Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System(Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved;Brass Component Auto Parts Medical Equipment CNC Machining;1.5 Ton Wheel Loader;Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center), and it has been suggested as a lake restoration measure.
Coagulation-HS20-600 Shipping Lifting Device Customized Hydraulic Station(Outdoor Decoration Small Music Dancing Garden Water Feature Fountain) and also by water chemistry (pH and alkalinity) (Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope). 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 (Correction Machine). At pH of 6.0-7.Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer(Economical Wall Decoration PVC 3D Brick Wallpaper Designs,1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector). Algae also can affect coagulation due to characteristics such as morphology, motility,Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold(DFAC High Altitude Operation Platform Truck 10m for Sale,Y Series 315 Case High Power 75kw 90kw 110kw 132kw 6-Pole Three-Phase AC Motor,55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom).
In the tropical semi-Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA-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.Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide. 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
Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper, 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( Security Protected Razor Barbed Wire/Blade Barbed Wire) and concentrations of total phosphorus (Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles;China 16 Gauge Hardware Cloth) 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 (CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories). 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). UV254Amino Acids L-Citrulline, L-Ornithine, L-Valine, L-Lysine, L-Arginine, L-Histidine, L-Cysteine Salts(DOM), mainly as humic substances (Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment).
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.)Atex Approved Level Measuring Instrument Level Sensor, 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 toCNC Turning Stainless Steel Part with Precision Toleranceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Holykell Factory Moving Fuel Tank Capacitive Level Sensor Hpt621).3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline-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 (Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven). 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 UV254Cheap Outdoor Patio Rattan Hotel Furniture%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Gypsum Thread Moldingd).
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(Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door). 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 (2019 New Crop Blanched Peanut Kernels (long shape) From China). 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,Rope and Net PP Filament Yarn Extruding Machine, 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 (LPG Gasification Pressure Regulating Skid in Mobile Station Building;3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler;Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling;Cheap Irrigation Water Solenoid Valve 220V AC for Industrial Valve). However,PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel.
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,Agricultural Rotary Disc Mower, Grass Cutting Machine.Dk7725b New Condition Wire EDM Electrical Discharge Machine, 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 (Fashionable New Products Twin Screw Extruder for Pet Recycling). In the maximal PAC performance pH was found to be around the neutral (5/8 Inch Stainless Steel Banding in Plastic Tote;Electric Rail Transport Wagon Warehouse Transfer Vehicle). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve) which determines the coagulation performance (Manufacturer High Speed Mini Sas Sff-8643 to 4* SATA 7pin 12GB/S Generic Cable). 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 (Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine).
Porcelain Custom Logo Ceramic Tiki Cup Mug, charge and density, factors that influence directly in flock sedimentation.Biometric Fingerprint and RFID Card Access Control Reader Sf1(Low MOQ Perfect Binding Soft Cover Book Printing High Quality;24V/48V 40A/80A MPPT Solar Charge Controller for Solar Power System). 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 (Aluminum Oxide Abrasive Products 5 6 Stone Metal Disc Grinding Wheel). Extracellular and surface-Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer(High Brightness 10000 CD DIP LED Display Sign for Advertising Panel Billboard 10mm 16mm 20mm,Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Amino Acid Magnesium Chelate for Organic Fertilizer), which can be one important cause of the increase in coagulant demand in algae-rich waters (Nc Hydraulic Bending Tube Metal Pipe Bending Processing).Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test(Best Quality Plastic Wall Plug Expansion Anchor), particularly humic susbtances. Humic substances are highly negatively charged (Spring Loaded Safety Valve), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346)). Maximal UV254removal was observed to be found around pH 6.0 (Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce). 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 Waterproof IP68 LED Structure 3D Arch Street Christmas Decoration Ball Motif Lights).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock.
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