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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 (New 11ml Nail Polish Bottle with Brush and Cap,Clean Laser Machine Price). As a result, several chemical methods have been applied to control P internal loading worldwide (Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs;LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter;New Design Comfortable PU Cemented Men and Boy Sandal). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Plastic Water Bottle 750ml Tritan Drinking Bottle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Factory Hollow Pneumatic Piston Rod, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Aluminum Profile Section Producting Line),CNC Machining Duct Forging Stainless Steel Flange. 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 (10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine;D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People;1220X2440mm fashion Design Melamine Flakeboard/Particle Board). However alum may result in high concentration of residual Al and is strongly affected by temperature (Laser Therapy Apparatus Predominantly 810nm Laser Output for Laser Therapy Pain Relief) 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 (Anatomy Tissue Slides Factory OEM/ODM Products). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price;Soft Green Landscaping Grass Artificial Turf;Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers;L18/8693 Best Sales Professional 18inch Subwoofer 1200W New Product China Supplier;Drawing Design Extrusion Aluminum Profile Enclosures for Electronics Instruments;Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter;New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor).Chemical Carbon Plastic Frames V Bank Filter Activated Carbon(Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem;Cnc Machine Part;Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Lab Pipette Tips with Good Quality Low Price), and it has been suggested as a lake restoration measure.
Coagulation-10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom(Ce Approved Disposable Paper Mask) and also by water chemistry (pH and alkalinity) (Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage). 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 (1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). At pH of 6.0-7.Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India(Single Color Twill Tapes Automatic Screen Printing Machine Supplier,Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set). Algae also can affect coagulation due to characteristics such as morphology, motility,Fresh Mung Bean Filling Stand-up Pouch Packing Machine(Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses,Top Quality Cleaning Cloth Microfiber Hair Salon Towel,Auto Hand Dryer).
In the tropical semi-Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order-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.Newest Robot Vacuum Cleaner with GPS, Camera, Built-in Virtual Wall. 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
Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV, 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(HPMC 200) and concentrations of total phosphorus (Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump;tunnelcutter.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 (Low Price & High Quality Stainless Steel X-ray Lead Door). 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). UV2541616 Aluminum LED Strip Channel Surface Mount LED Extrusion(DOM), mainly as humic substances (High Carbon Steel Wire Lead Patenting Phosphate Production Line).
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.)600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag, 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 toDepilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Un/Uhs/Dz PU Dust Proof Oil Seal Hydraulic Seal).Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce-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 (Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment). 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 UV254High Pressure Zirconia Ceramic Piston Rod Pump Ceramic%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Cheap Soccer Game Table Foldable Football Table with L Shape Leg). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (slocable solard).
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(Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer). 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 (Puffed Food Automatic Vertical Packing Machine). 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,Brown Shoes High Quality Strong Protection Working Shoes, 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 (A76 Nordic Living Room Dining Room Furniture;Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System;D2-825 800W 250W 2CH DSP Active Plate Amplifier for Bi-AMP Speaker). However,700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346).
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,4we5 Electrically Operated Directional Control Valves.Single Head High Speed Tubular Cap Embroidery Machine (TLC901), 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 (90ml Cool Designer Perfume Glass Bottle with Surlyn Cap). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle;Fr-218 BOPP Packing Tape Slitting Rewinding Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock) which determines the coagulation performance (Air Vent Phone Holder High Quality Supplier). 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 (Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery).
Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System, charge and density, factors that influence directly in flock sedimentation.High Speed LDPE Polyethylene Plastic Film Extrusion Machine(Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line). 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 (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel). Extracellular and surface-Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event(Acrylic Makeup Organiser Brush Holder with Beauty Cosmetic Sponge Puff Drawers,Free-Maintenance Motor Design White Light PTZ Security Cameras). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Plastic Cover Aluminum A60 7W E27 LED Global Bulb), which can be one important cause of the increase in coagulant demand in algae-rich waters (Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery).Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe(UPVC Rigid Water Supply Drain Pipe Production Line), particularly humic susbtances. Humic substances are highly negatively charged (Stainless Steel 201/304 120kg Visible Sliding Door Hanging Wheel), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Temperature Multi-Jet Ultrasonic Heat Measure Meter). Maximal UV254removal was observed to be found around pH 6.0 (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine). 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 (OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Caprolactam Grade Ammonium Sulphate (21%Min).
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