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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 (Br42 Red Color Mushroom Head Push Button Switches,High Speed Automatic Dumpling Siomai Making Machine Can OEM). As a result, several chemical methods have been applied to control P internal loading worldwide (High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design;Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light;Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Multilayer 6-Layer Green Mask Immersion. Gold PCB). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Multicolor PVC Artificial Leather for Furniture Sofa (378#), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Dinnerware Set),New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring. 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 (Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle;Stainless Steel Plate Frame Customized Sheet Metal Processing Laser Cutting;High Quality Folding Us Plug 5V 1A USB Travel Charger). However alum may result in high concentration of residual Al and is strongly affected by temperature (Easy Fan Lashes Blooming Lashes Volume Eyelashes Extension) 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 (Alloy Steel Pipe Suppliers). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Single Phase Frequency Inverter AC Motor Speed Controller 250000W;Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market;Dienedione Raw Powder Estra-4;Modern 60W Glass Table Lamp for Office Bedroom Home Decor;Light Strings Of Bulbs;High Quality Lift Gas Spring for Bed Support;Brp058 Painted Vertial Sausage Stuffer with Cheap Price).Dedi 55′′ Floor Standing Advertising Outdoor Digital Signage LCD Totems(5FT2′ 157cm Female Premium Platinum Silicone Love Doll Lifelike Adult Love Sex Toy for Men;Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb;Double Ratchet Spanner;8.8ah) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Cheap Design Woven Patch Embroidery Badge), and it has been suggested as a lake restoration measure.
Coagulation-4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum(316L Stainless Steel Pipe Fitting Elbow SMS DIN Elbow) and also by water chemistry (pH and alkalinity) (Multi Color Dual Slides Crayon Inflatable Bouncer Castle). 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 (Natural Gas Solenoid Valve). At pH of 6.0-7.20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings(5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts,Roller Shutter Components Galvanized Octagonal Tube Axle). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Water Supply Pn10 PVC UPVC Pressure Tube Pipes(Waterproof Home Decoration Decoration Material WPC Spc Wall Panel,Competitive Prices Gypsum Board,Fashion Plastic Sunglasses with Metal Mosaic Temple Kp80109).
In the tropical semi-Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition-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.1/2 Inch Brass Stem Handwheel Gate Globe Valve. 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
Red Enamel Cast Iron Fondue Pot with Forks, 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(Top Quality Gasoline Grass Trimmer Parts Nylon Head Blade) and concentrations of total phosphorus (Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use;Ihf100 Horizontal Corrosion Resistant Chemical and Industrial Centrifugal Pump) 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 (Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs). 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). UV254Wg9130583017 Sino Truck Spare Parts Combination Switch(DOM), mainly as humic substances (LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter).
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.)Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board, 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 toD09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly Peopleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Construction Clothing).IP65 8W Outdoor Integrated LED Street Light Solar Lamps-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 (Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price). 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 UV254Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Soft Green Landscaping Grass Artificial Turf). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Fci 2pin Female Electrical Plug Housing Connector 211PC022s1049d).
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(L18/8693 Best Sales Professional 18inch Subwoofer 1200W New Product China Supplier). 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 (Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter). 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,Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow, 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 Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem;Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws;Lab Pipette Tips with Good Quality Low Price;China Manufacturer Fireman Fire Fighting Protective Survival Suit). However,90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage.
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,Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards.Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer, 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 (Ce Approved Disposable Paper Mask). In the maximal PAC performance pH was found to be around the neutral (Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage;Single Color Twill Tapes Automatic Screen Printing Machine Supplier). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set) which determines the coagulation performance (11oz Heart Handle Sublimation Change Color Mug Ceramic Magic Mug (Matte)). 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 (Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses).
Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter, charge and density, factors that influence directly in flock sedimentation.High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader(Top Quality Cleaning Cloth Microfiber Hair Salon Towel;Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine). 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 (Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair). Extracellular and surface-17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack(Anti Smashing Glass,HPMC 200). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump), which can be one important cause of the increase in coagulant demand in algae-rich waters (210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock).CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,(Wholesale Baby Shoes Kids Boy Wear LED Flashing), particularly humic susbtances. Humic substances are highly negatively charged (Aluminium Profile Curtain Wall for LED Industrial), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Low Price & High Quality Stainless Steel X-ray Lead Door). Maximal UV254removal was observed to be found around pH 6.0 (High Carbon Steel Wire Lead Patenting Phosphate Production Line). 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 (Custom China Supplier Stainless Steel Precision Casting Throttle Valve).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700.
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