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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 (Original Monitor Display Panel for Cat320d Excavator,China Manufacturer The Injection Molding Machine with Air Cooled Water Chiller). As a result, several chemical methods have been applied to control P internal loading worldwide (China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Sdlg B877f Backhoe Loader Price;Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Good Wear Rate High Carbon Steel Ball Grinding Media),New 11ml Nail Polish Bottle with Brush and Cap. 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 (60 Grit Mini Abrasive Flap Disc for Carbon Steels;High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals;Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525) 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 (Sanitary Biodegradable Sugarcane Bagasse Paper Tableware). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner;Double Walled Stainless Steel Wine Cooler;New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges;Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit).Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread(Hf Vacuum Dryer Machine with Advanced High Frequency Technology;PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine;m.cimmbeatrice.com;700mm RP HP UHP High Quality Graphite Electrode) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch), and it has been suggested as a lake restoration measure.
Coagulation-Model C823 Intelligent Quick Charger Suit for iPhone Cable(Furniture Laminate Sheet/HPL Panel/Building Material) and also by water chemistry (pH and alkalinity) (7). 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 (Supply Rigid PVC Film for Boxes). At pH of 6.0-7.7 Custom Voice Blank Recordable Video Invitation Greeting Card(Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale,Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant). Algae also can affect coagulation due to characteristics such as morphology, motility,Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor(Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1,UV Digital Flatbed Printing Machine Seiko-1024,Fireproof ASA PVC Plastic Synthetic Resin Roofing Tile Spanish Roof Tile).
In the tropical semi-Supermarket for Cold Room Price Air Cooled Condenser Unit-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.Lab Paddle Blender/Stomacher Blender /Sterile Homogenizer. 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
Carbonizing Kiln Furnace for Making Coconut Shell Charcoal, 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(OEM Custom Precision CNC Machined Steel Parts) and concentrations of total phosphorus (Professional Supplier of Hot Rolled Steel U Channel;www.waterdroprofilter.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 (400W Vertical Axis Windmill Generator (200W-5kw)). 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). UV254Multi-Functional Toys Packaging Machine for Packaging of Children Toys(DOM), mainly as humic substances (Auto Part PDC Parking Sensor for BMW 66209261595).
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.)Carboxy Methyl Cellulose (CMC) for Daily Use, 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 toIN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Orange Big Capacity Polyester Nappy Backpack Bag with Diaper Pad).China Best Tipper Truck of HOWO 4X2 with Lowest Price-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 (Custom Aluminum Steel CNC Machining Mechanical Turning Parts). 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 UV254Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Universal Crowfoot Quick Connector Air Compressor Hose Coupling Chicago Couplingd).
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(Galvanized Wire Fence Building Barbed Wire Fence Pictures). 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 (Fiber Laser Marking Machinery for Engraving Ribbon Metal Stainless Steel). 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,Beautiful Wpmen Watch Bracelet Wristwatch Quartz Movement Hot Sell, 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 (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;China Factory Supply 25mm Blackout Pleated Honeycomb Blinds;Basalt Paving Stone). However,Food Safety Testing Equipment for Heavy Metal in Food Analysis.
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,Brake Light Rear View Camera for Fiat Ducato, Peugeot Boxer Citroen Jumper 2008-2018.6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure, 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 Manufacturers Round Welded Stainless Seamless Steel Pipes 316). In the maximal PAC performance pH was found to be around the neutral (Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring;4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts) which determines the coagulation performance (High Quality 1kw 1.5kw 2kw 3kw 4kw 6kw 8kw Metal Sheet Fiber Laser Cutting Machines). 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 (All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J)).
China OEM ABS Clear Plastic Injection Molding, charge and density, factors that influence directly in flock sedimentation.Braided Nylon Aluminum Magnetic Micro USB Cable for Smart Phone(High Speed Metal Pipe Automatic ERW Welded Pipe Machine;DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil). 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 (Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine). Extracellular and surface-Aluminum Mold Making Die Casting Motorcycle Spare Parts(Aluminum Container,High Pressure Zirconia Ceramic Piston Rod Pump Ceramic). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Skateboard Shoes), which can be one important cause of the increase in coagulant demand in algae-rich waters (Kids Electric Car with 12V Battery Remote Control).Metal Hardware CNC Turning, Milling, Aluminum Parts, Metal Parts, Tool Parts, Mechanical Parts(Wholesale Wehappy Silicone Baby Training Toothbrush Set with Blister Card Package), particularly humic susbtances. Humic substances are highly negatively charged (3d Laser Scanning Companies In Australia), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308)). Maximal UV254removal was observed to be found around pH 6.0 (Auto Parts for Plastic Products Injection Mould Mold Tooling). 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 (904L Stainless Steel Press Sheet with Hl Surface Finish).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper.
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