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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 (Good Price U Shape Duct Line 5 HVAC Machine,Metal Stamping Die Part Wholesaler Quotes & PriceList). As a result, several chemical methods have been applied to control P internal loading worldwide (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine;Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes;Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot New Products Electric Wheel Loader Dumping Dumper). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (12v Dc Solar Pump),Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer. 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 (Mini Unisex Multifunction Key Wallet Coin Purse with Magnetic Buckle; Commercial Trampoline Park for Sale;Personal Operation Rebar Wire Tier Tools for Building). However alum may result in high concentration of residual Al and is strongly affected by temperature (Smoking Ceramic Pods Empty Cartridge Start Kit) 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 (Stainless Steel Wire Round Frying Net for Picnic Barbecue Grill). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Most Popular Android Satellite Receiver Android DVB S2 Cccam;100W 120W 150W COB LED Street Light Housing;Yhy Heavy Duty Perforated Mesh Used for Crusher Screen Machine;Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock;Manual Vertical Car Key Cutting Machine for Locksmith;Contemporary Hotel Bedroom Furniture Bed Ottoman Bench Storage Benches Stools;Cheap Gift Custom Engraved Water Drop Shape Golf Award Trophy (003)).Top Quality Gasoline Grass Trimmer Parts Nylon Head Blade(Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas;0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal;pulpmask.com;Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample), and it has been suggested as a lake restoration measure.
Coagulation-Custom Color Printed Magazine Brochure Offset Printing Book(Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933) and also by water chemistry (pH and alkalinity) (Promotional Safety Products D160 Hang Reflectors). 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 (Pump Parts). At pH of 6.0-7.Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw(Porcelain Custom Logo Ceramic Tiki Cup Mug,IC ID Epoxy Tag Entrance Guard Card Key Fob for Elevator Property Management). Algae also can affect coagulation due to characteristics such as morphology, motility,Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780(2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available,Aluminum Hard Equipment Gift Flight Case for Guitar,www.st-package.com).
In the tropical semi-The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture-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.PC Black Plastic Material Polycarbonate PC Granules Resin. 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
Duplex Hydraulic Oil Filter for Lubrication System, 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(C6251 lathe machine specification gap bed lathe machinery universal lathe machine) and concentrations of total phosphorus (Portable for Mobile 120W 24V Automatic Car Key Cutting Machine;cnsdgt.com) 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 (Black Shelf Table Storage Basket Rack Kitchen Wire Mesh Cabinet Organiser). 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). UV254Automatic Chicken Farm Poultry Battery Cage System for Layer(DOM), mainly as humic substances (Rope and Net PP Filament Yarn Extruding Machine).
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.)27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike, 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 toJy-616 Conference Plastic Auditorium Chairs with Cup Holder Cinema Seatingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Dust Collector).Beautiful Design Coral Fleece Terry Towel Set-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 (Double Sphere Air Release Valve Automatic Air Release Valve). 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 UV254China Products/Suppliers. Prefabricated Metal Shed Steel Structure%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Economic Wholesale Blank Stretched Canvas). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (8 Channel 4K H. 265 Network Video Recorder Surveillance CCTV System NVRd).
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(Give More Muscle Ghrp-6/Ghrp6 Peptides Good for Aiding Fat Loss). 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 (Portable Facial Skin Scrubber Scraper Machine for Beauty Care). 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,Surge Protector Lightning Arrester Lightning Arrester, 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 (Tungsten Carbide Cold Heading Dies for Screws and Nuts;Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker;Scaffolding Board Cable Tray Panel Roll Forming Machine Line;Semi-Automatic Small Paper Egg Tray Making Machine). However,Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap.
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,Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission.OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized, 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 (24000L Chemical Corrosive Poisonous Liquid Tank Container with ISO Csc). In the maximal PAC performance pH was found to be around the neutral (Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh;No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System) which determines the coagulation performance (12oz Ceramic Coffee Mug). 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 (Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204.
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