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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 (Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter,50 Hz-10 Supplier & Factory). As a result, several chemical methods have been applied to control P internal loading worldwide (Health Food Krill Oil Softgel for Antioxidation;Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine;E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Farrowing Crate Galvanized Swine Farrowing Crates). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,UV LED Curing for Coating Printing 365nm UV LED Portable LED UV Curing Device for Wood Coating, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Foley Catheter Balloon),China Factory Price 6 Axles Tractor Truck Trailer. 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 (Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment;Cheap Soccer Game Table Foldable Football Table with L Shape Leg;Competitive Price Corrugated Tubing with Braid Layer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer) 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 (0.5mm Wearlayer Wear Resistance Anti-Scratch WPC Flooring). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Puffed Food Automatic Vertical Packing Machine; Customized Fancy Printing Adhesive Paper Label Sticker;TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor;A76 Nordic Living Room Dining Room Furniture;Products: Metal Stamping, Metal Stamping Part, Stamping Part, Metal Part;Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System).2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)(90ml Cool Designer Perfume Glass Bottle with Surlyn Cap;Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle;Electric Scooter Singapore Law;Fr-218 BOPP Packing Tape Slitting Rewinding Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock), and it has been suggested as a lake restoration measure.
Coagulation-304, 316 Slot Stainless Steel Tube with Glass(Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery) and also by water chemistry (pH and alkalinity) (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal). 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 (Polyester Nonwoven Double Colour Velour Jacquard Indoor Carpet). At pH of 6.0-7.Giant Christmas Socks Carnival Amusement Park Inflatable Slide(Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line,Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel). Algae also can affect coagulation due to characteristics such as morphology, motility,Multifunction Massage Rainfall Shower Column with Five Functions(Free-Maintenance Motor Design White Light PTZ Security Cameras,Plastic Cover Aluminum A60 7W E27 LED Global Bulb,Vacuum Packaging Weight Loss Slimming 100kHz Cavitation Machine).
In the tropical semi-Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller-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.Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative. 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
Easywell & Minston Electric Platform Scale with Height Meter BS-200lp, 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 Temperature Multi-Jet Ultrasonic Heat Measure Meter) and concentrations of total phosphorus (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine;10w 20w 30w 50w Fiber Laser Marking 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 (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine). 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). UV254Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder(DOM), mainly as humic substances (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar).
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.)Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085), 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 toCustom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Sliding/Extensible Screen Style).50-5000L Commercial Craft Beer Brewery Equipment-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 (New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice). 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 Cup Set Handmade Coffee Cup and Saucer Set%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Tensile Sharp Razor Barbed Wire for Security Fencing). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Right Angle Drilld).
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(High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head). 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 (Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve). 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,Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine, 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 (Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel;Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace;Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven;High Quality Decorative Gift Silver Customized Police Keyring (186)). However,Coconut Shell Activated Carbon for Drinking Water Treatment.
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,High Quality CNC Turning Center Parts Machinery Auto Parts.Customized Acrylic Plastic Sign Board Design Customized Size, 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 (Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype). In the maximal PAC performance pH was found to be around the neutral (Automatic Mango Juicer Filling Machine / Canned Juice Production Line;Low-Cost Tree Stump Crushing Machine with Widely Using). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Plant Stands & Accessories Glass Hanging Flower Pot Bracket) which determines the coagulation performance (Divya Diamond Tools). 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 (Seamless Circular/Square/Rectangular Steel Tube).
1W Colorful Garden Park Plaza Lawn Underground Lamp, charge and density, factors that influence directly in flock sedimentation.Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery(Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z;Lightweight New Design Girl Fashion Bags Children School Backpack). 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 (Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier). Extracellular and surface-Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing(Galvanized/Finish Plain/Toothed/I Type Steel Bar Grating for Floor Walkway,New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Round 10W LED CCT Tuneable Dimmable Down Lights), which can be one important cause of the increase in coagulant demand in algae-rich waters (Customize Cartoon Printing Logo Brand Silicone Swim Cap).SKF Bearing, Miniature Ball Bearing for Window Sliding Rollers (626ZZ)( Citycoco), particularly humic susbtances. Humic substances are highly negatively charged (Click Lock 4mm Spc Flooring), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Type F High-Rise Clip Drive/Worm Hose Clamp). Maximal UV254removal was observed to be found around pH 6.0 (28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket). 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 (New Version Breakage-Proof Multihead Weigher for Biscuits).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers.
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