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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 (Scarifier Loosener Ripper Horizontal Rotary Cultivator Tiller,Hair Fiber Concealer Hair Building Powder for Thinning Hair). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63;New Product PVC Insulation Tape;GM320 Digital Infrared Thermometer Non Contact Infrared Thermometer IR Laser Point Gun -50~330 Degree). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Food Grade Clamped Tubular Sight Glass in Stainless Steel). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Woma Acrylic Shower Panel Cubicle Room for Old People (Y697A)),Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses. 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 (Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights;57-5 Micron Micro Powder Mill Pulverizer Grinding Plant;Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print) 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 (Laco Aluminium Flux Paste). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.;Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump;Large Industrial Ceiling Fan with External Rotor Motor Drive;High Quality Non-Standard Metal Components Precision Machining Mold Parts;All House Generator;Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine;800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights).Rechargeable Battery Powered Indoor WiFi Camera with Custom APP(Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer;Building Hot Rolled C Purlin C Channel Steel Price;Home Appliance Decor Flame LED Electric Fireplace Insert Wall Mounted Heater;Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PP Surface Self Adheisve Roof Underlayment), and it has been suggested as a lake restoration measure.
Coagulation-Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet(High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel) and also by water chemistry (pH and alkalinity) (Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price). 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 (Electric Heating Lab Two Roll Mixing Mill). At pH of 6.0-7.Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine(Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing,Jbz-22D Automatic High Speed Paper Cup Forming Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Professional Palm Handheld Veterinary Ultrasound Diagnostic System( PN20),Automatic Chicken Farm Poultry Battery Cage System for Layer,Cheap Catalogue Printing).
In the tropical semi-Custom Logo Small Beer Mug One Ounce Mini Stein Glass-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.PVC Coated Galvanized 12 Guage Iron Baling Wire. 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
Kh CNC Plasma Cutting Machine 1530 CNC Controller, 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(Cheap Prise Solid Carbide Reamers for Drilling Hole Factory Outlet) and concentrations of total phosphorus (UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode;Cable Tie Ss316 India) 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 (Color Coated Prepainted Aluminum Sheet/Coil). 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). UV254High Quality Anti-UV Artificial Garden Grass Carpet(DOM), mainly as humic substances (High Quality Wooden Cabinet Design Shoe Display Unit for Shop).
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.)Sw Type BOPP Packaging Adhesive Tape Coating Machine, 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 toOrganice Ball Fertilizer Granulation Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(12mm 6V 12V 24V 220V LED Anti-Vandal Waterproof Metal Indicator Light Signal Lamp).19mm Fancy Plywood for Door Use and Whole House Decorative-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 (Outdoor Fitness Equipment Gym Chilren′s Teeterboard). 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 UV254Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ruipai High Quality Plastic Recycling Extruder). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Double Skin Ahud).
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(40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer). 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 (Warehouse Storage Industry Rack Mezzanine Floor Platform). 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,High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos, 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 (Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair;Hot Sale Pet Strap Straps Strapping Band Machine/Extrusion Line/Extruder;Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778);Stand-up BBQ Sauce Bag with Spout). However,Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift.
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,Stainless Steel Expanded Metal Mesh for Industrial.Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display, 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 (Ceiling Type). In the maximal PAC performance pH was found to be around the neutral (Custom Aluminum/Aluminium Extruded Housing by Using CNC Machining;Electroplated Diamond 200mm Circular Saw Blade for Concrete Cutting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Automatic 2 Color Screen Printing Machine for Bottle Lids with UV Curing System) which determines the coagulation performance (Small Size Panel Computer Desk/Table with Keyboard Tray Bookshelf). 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 (Europe Quality ACP Aluminum Composite Panels for Building Decoration).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Plastic Valve with The Membrane Heat Welding Machine.
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