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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 (Customized Wire Mesh for Decorative Garden Fence,Cummins Diesel Generator Spare Parts Price List). As a result, several chemical methods have been applied to control P internal loading worldwide (Fan Cooling Oval Design Commercial Cake Display Showcase Fridge;China Qingdao Factory Interlocking PVC Garage Floor;Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Double Arm Medical Pendant for Anesthesia (HFP-DS240/380)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (3V-12V 30-34V High Power 10W 20W 30W 50W 100W Warm White Cold White RGB COB LED Chip),Wholesale Foldable Desk Silicon Mobile Phone Stand. 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 (High Quality Galvanized Welded Wire Mesh Panel Roll;Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event;Ce Eco-Friendly 24V Electric Motor Operated SS304 Water Flow Control Valve for Drinking). However alum may result in high concentration of residual Al and is strongly affected by temperature (Incoloy 825 Pipe for Industry Application) 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 Chiller Manufacturers Water Chiller). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Type Portable 380V Electric Winch in Stock;Custom A4 Size Plastic PP Clear File Button Folder;Hook Vintage Weathered White Wall-Mounted Wood Coat Rack with Chalkboard Labels;250ml Empty Refillable Pet Material Plastic Shampoo Bottle;Asset Management S50 S70 NFC RFID Tag Printed Adhesive Label;Laparoscope Instrument Laparoscopy Set for Ectopic Pregnancy Surgery;Industrial Paraffin Wax/Powder/Slab/Paraffin Wax Chemical Formula).300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131(Ouwave HVAC Scent Fragrance Systems Aroma Diffuser Electric Scent Machine;120 Grit Sand Blasting Media/Sandblasting Abrasives/Almandite/Garnet Sand 80 for Waterjet Cutting;Ip65 Led Area Light High Quality Supplier;Ci/Di/Ss/C954 Al Bronze Body Double Flange Butterfly Valve Pn10 Pn16 Pn25) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Modular Concrete Batching Plant by Twin Shaft Mixer 3000/2000), and it has been suggested as a lake restoration measure.
Coagulation-Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle(Virtual Reality Egg Game Machine Amusement Riding Machine for Sale) and also by water chemistry (pH and alkalinity) (Ad-P720 Hot-Selling Perfume Glass Bottle 100ml). 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 (Bike for Kids). At pH of 6.0-7.American Double Hung Thermal Break Aluminum Window in China(Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair,Hidrotek Water Filter Cartridge with Sediment Carbon). Algae also can affect coagulation due to characteristics such as morphology, motility,Fashion Design Steel-Wood Large Conference Table(9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting,Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price,Money Clip Travel Work Slim Wallet for Passport Holder).
In the tropical semi-Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck-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.Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids. 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
Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting, 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(High Quality Polyurethane Adhesive for Scrap Sponge) and concentrations of total phosphorus (Carbon Steel Carry Idler Belt Conveyor Guide Roller;Aluminum Foil Lid Punching Machine) 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 (2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card). 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). UV254OEM Custom Plastic Injection Mold for Mobile Phone Case(DOM), mainly as humic substances (Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire).
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.)China Manufacrure Mobile Asphalt Batch Mix Plant for Sale, 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 toDish Plate Dryer and Sterilizer 60liter Using UV and Ozoneas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(1040 Steel Carbon Steel Material Composition Forging Grain Structure).Synthetic Fiber Filter Rolls Filter Media for Air Conditioning-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 (Transparent 240W SMD 3030 Outdoor LED Flood Lamp). 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 UV2541600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ISO Factory of Disc Cutter for Tunnel Boring 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 (Plastic Bottle Fruit Juice Hot Filling 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(Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966). 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 (Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture). 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,THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca, 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 (Electric Multifunction Motorized Lifting and Rotated Medical Equipment Product Fth-005;Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds;2019 Henan Factory Manufacturer Industrial Wood Chipper Wood Chipper Shredder;Micro USB Female B-Type Receptacles Verticle DIP). However,China Manufacturers Round Welded Stainless Seamless Steel Pipes 316.
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,Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price.Foshan Manufacturer Bathroom Glass Sliding Door Roller, 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 (Banbury Rotors 3L Lab Plastic and Rubber Mixer Machine). In the maximal PAC performance pH was found to be around the neutral (P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption;27.5er Sram 12speed carbon Mountain Bike with Air Suspension Fork). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ce Approved Gobal Warranty 200kVA 100kVA 50kVA 25kVA Diesel Generator Price) which determines the coagulation performance (Colorful Heat Wrap Cap Seal Sleeve Metal Roll Foil Label PVC Shrink Wine Tin Capsule for Bottles). 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 (Aluminum/Aluminium Foil/Coil for Retort Pouch/Bag/Stand-up Pouch A8079/1235/8011-Soft 5.9/6 Microns).
4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening), charge and density, factors that influence directly in flock sedimentation.Industrial RO Water Purification-1500gpd with Black Cabinet (0.25T/H)(High Purity Medical Psa Oxygen Generator/Concentrator Manufacurer with Low Cost;925 Fashion Silver Jewelry with Zircon Set Ring Wholesale). 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 (Full Automatic Egg Tray Manufacturing Machine). Extracellular and surface-Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller(Picnic Bag For 2,Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Speed HDMI to HDMI Cable 1.4 Version 1080P 3D Standard 2.0), which can be one important cause of the increase in coagulant demand in algae-rich waters (LPG Filling Station (Volume Optional) Gas Station with Dispenser Mobile LPG Skid Mounted).Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition(CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts), particularly humic susbtances. Humic substances are highly negatively charged (20mm Metal Laser Cutting Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (19′′ Smart Table Android Windows PC Touch Screen Kiosk). Maximal UV254removal was observed to be found around pH 6.0 (High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos). 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 (Hot Selling Construction Machine 50cbm/H Ready Mixed Concrete Mixing Plant).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Manufactured Goods PPGI Coil Corrugated Steel Sheet.
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