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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 (Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home),Dia 3-20 mm Tungsten Oil Feed Rod for Plug Gauge Cemented Carbide Rods). As a result, several chemical methods have been applied to control P internal loading worldwide (Original Monitor Display Panel for Cat320d Excavator;China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Sdlg B877f Backhoe Loader Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,50-5000L Commercial Craft Beer Brewery Equipment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Modern Living Room Indoor Furniture Rattan Corner Sofa Set),China Cup Set Handmade Coffee Cup and Saucer Set. 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 Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts;60 Grit Mini Abrasive Flap Disc for Carbon Steels;High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals). However alum may result in high concentration of residual Al and is strongly affected by temperature (Stone Plastic Composite Spc Rvp Flooring Floor Mat 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 (Ac Mini Contactor). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525;Micro Water Tank Level Transducer for Wall Hung Gas Boiler;High Temperature Alternative Stainless Steel Band in Different Package;Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp;Auto Slack Adjuster;Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner;New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges).Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine(Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Hf Vacuum Dryer Machine with Advanced High Frequency Technology;China Metallurgy Transport Vehicle;PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (700mm RP HP UHP High Quality Graphite Electrode), and it has been suggested as a lake restoration measure.
Coagulation-Coconut Shell Activated Carbon for Drinking Water Treatment(Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch) and also by water chemistry (pH and alkalinity) (Furniture Laminate Sheet/HPL Panel/Building Material). 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 (Brother Label 11209). At pH of 6.0-7.High Quality CNC Turning Center Parts Machinery Auto Parts(7,Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Customized Acrylic Plastic Sign Board Design Customized Size(Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant,Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1,Diamond Blade For Miter Saw).
In the tropical semi-1W Colorful Garden Park Plaza Lawn Underground Lamp-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.Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery. 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
Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing, 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 Compair Air Compressor Air Filter 50273) and concentrations of total phosphorus (OEM Custom Precision CNC Machined Steel Parts;Professional Hot Sell Trimless Recessed LED Down Light-R6310) 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 (Multi-Layer HDPE PE PPR Pipe Production Line). 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). UV254SKF Bearing, Miniature Ball Bearing for Window Sliding Rollers (626ZZ)(DOM), mainly as humic substances (400W Vertical Axis Windmill Generator (200W-5kw)).
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.)Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers, 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 toKfc Macdonald Food Grade Convenient Disposable PE Gloveas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Sports Handbags Gym Bag with Shoes Compartment Travel Duffel Bag Shoulder Bag for Men and Women).Eco-Friendly Unbreakable Drinking Cup Shatterproof Silicone Wine Cups for Party-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 (OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose). 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 Most Professional Factory 316L Stainless Steel Round Seamless Decorative Pipe Tube%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Aluminum Steel CNC Machining Mechanical Turning Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (5ton Hydraulic Power Unit Single Drum Winch for Saled).
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(2 Ton Brand New Small Cheap Backhoe Loader for Sale). 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 (Galvanized Wire Fence Building Barbed Wire Fence Pictures). 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,Manufacturers 1000W AC/DC Converter Car Power Inverters, 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 (3.0V 4mm Diameter Coreless Mini Strong Vibration Motor with Bracket;Combustibility Analyzer Flame Testing Equipment for Building Material ISO 11925;35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck;Electric Cleaner). However,13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture.
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,Portable Metal and Nonmetal CNC Fiber Laser Marking Machine.Fast Thermal Cycling High Heat Temperatures Resistance 99% Alumina Ceramic Insulator Rod, 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 (China Factory Supply 25mm Blackout Pleated Honeycomb Blinds). In the maximal PAC performance pH was found to be around the neutral (China Manufacturers Round Welded Stainless Seamless Steel Pipes 316;Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring) which determines the coagulation performance (Soybean Fruit Fresh Chili Paste Sauce Filling Machine). 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 (Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Granular Fertilizer Potassium Sulphate/NPK/Compound Production Line.
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