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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 ( Table Gas Stove,Custom Non-Woven Shopping Bag High Quality Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services;Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price;Supporting DDR4 RAM Intel Core I5 Mini PC Computer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Vodafast A2 Stainless Steel Channel Nuts with Long Spring). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Lab Equipment Weathering Resistance Arc Xenon Lights Aging Testing Chamber),Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories. 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 (Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine;Custom Aluminum Stainless Steel 90 Degree Angle Brackets;5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter). However alum may result in high concentration of residual Al and is strongly affected by temperature (Aluminum/Cooper/Galvanized Tube Precision Pipe Making 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 (Industrial Water Cooled Scroll Chiller for Cooling Food). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s;OEM Aluminum Cutting Welding Stamping Shaping Fabrication;Outdoor WPC Wood Plastic Composite Fence Board with High Quality;Fiberglass Water Park Spray Playground Equipment for Sale;ruichirobot;Dk7725b New Condition Wire EDM Electrical Discharge Machine;Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer).Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer(CO2 Laser Engraving Cutting Machine for Acrylic;Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter;gym equipment;0.5m-2.0m Wire Mesh Belt Shot Blast Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Plastic Banbury Mixer for Laboratory), and it has been suggested as a lake restoration measure.
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In the tropical semi-Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780-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.The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture. 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
PC Black Plastic Material Polycarbonate PC Granules Resin, 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(China Digital Type Lithium Battery Crush Testing Machine Price) and concentrations of total phosphorus (38cc Petrol Chain Saw Wood Cutting Machine;Tantalum Tungsten Alloy Sheet) 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 (Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board). 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). UV254Duplex Hydraulic Oil Filter for Lubrication System(DOM), mainly as humic substances (Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP).
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.)Automatic Chicken Farm Poultry Battery Cage System for Layer, 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 toPortable Marking Machine Table for Height Adjustmentas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3*7 MIFARE DESFire EV1 2K 4K RFID Inlay for Smart Card Making).27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike-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 (PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank). 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 UV254Beautiful Design Coral Fleece Terry Towel Set%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Construction Equipment Full Automatic Concrete Block Making Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Heavy Duty Wood Planer Thicknesser with Helicall Cutter Headd).
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(100kw Electric Power Plant or Biogas Gas Engine Generator Price). 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 (Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck). 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,China Products/Suppliers. Prefabricated Metal Shed Steel Structure, 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 (Accessories of Anchoring Round 2 Holes Anchorage Block with Wedges;China Manufacture 2mm3mm5mm Thickness Round Wall Mirror for Sale;G95 LED Filament Bulb Light Lamp 8W 110-130V/220-240V Edison Bulb with Ce RoHS;3D Wall Covering Material Wooden Color Wall Cladding PVC Laminated Wall Panels). However,Surge Protector Lightning Arrester Lightning Arrester.
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,Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap.Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission, 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 (Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer). In the maximal PAC performance pH was found to be around the neutral (Amusement Park Outdoor Water Park Slide Boat Playground for Sale;Purity Veterinary Pharma Grade Albendazole with Competitive Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Pin-Barrel Rubber Sheet Lining Extruder System Machine Production Manufacturing Line) which determines the coagulation performance (Double Wire Hose Clips Adjustable Hose Clamps Hoop Plumbing Fastener). 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 (Amino Acids L-Citrulline).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet.
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