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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 (Lab Pipette Tips with Good Quality Low Price,Automatic Battery Poultry Equipment Chicken Layer Cage). As a result, several chemical methods have been applied to control P internal loading worldwide (Ce Approved Disposable Paper Mask;Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage;Single Color Twill Tapes Automatic Screen Printing Machine Supplier). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Concrete Drill),FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound. 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 (Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses;Top Quality Cleaning Cloth Microfiber Hair Salon Towel;Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair) 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 (PVC Corrugated Roof Sheet Tile Panel Plastic Extrusion Making Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (HPMC 200;Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump;210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock;Wholesale Baby Shoes Kids Boy Wear LED Flashing;200GSM Nonwoven Polyester Geotextile for Railway Construction;Low Price & High Quality Stainless Steel X-ray Lead Door;High Carbon Steel Wire Lead Patenting Phosphate Production Line).Handrail Fitting / Stainless Steel Round & Square Tube Connector(Custom China Supplier Stainless Steel Precision Casting Throttle Valve;Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter;Rg59 Premade Connector Cable For Cctv Camera;Health Food Krill Oil Softgel for Antioxidation) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine), and it has been suggested as a lake restoration measure.
Coagulation-Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car(E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits) and also by water chemistry (pH and alkalinity) (Farrowing Crate Galvanized Swine Farrowing Crates). 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 (Wholesale Beautiful Sweet Great Quality Girl Ballet Shoes). At pH of 6.0-7.BRT Gasoline Log Splitter 22 Ton Firewood Processor(Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment,Cheap Soccer Game Table Foldable Football Table with L Shape Leg). Algae also can affect coagulation due to characteristics such as morphology, motility,Android Data Cable Mobile Phone USB Cable Mobile Phone Cables(Competitive Price Corrugated Tubing with Braid Layer,Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer,2ton Road Construction Equipment Telescopic Wheel Loader Like Multione).
In the tropical semi-Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press-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.Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook. 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
Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter, 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(TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor) and concentrations of total phosphorus (A76 Nordic Living Room Dining Room Furniture;Sale Australia Mobile Food Trailer with Ce Customized Food Trucks) 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 (90ml Cool Designer Perfume Glass Bottle with Surlyn Cap). 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). UV254Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508(DOM), mainly as humic substances (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle).
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.)Transparent High Quality Building Glass Curtain Wall From China Suppliers, 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 toQr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metalas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Garden Weed Tool Cultivator Tiller).Professional Produce Dmp-430A Vacuum Tray Sealer-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 (Free-Maintenance Motor Design White Light PTZ Security Cameras). 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 UV254Cation Printing Effect Micro Fleece, Jacket Fabric (nautical blue)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Plastic Cover Aluminum A60 7W E27 LED Global Bulb). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pictures Of Ceramic Tiled).
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(UPVC Rigid Water Supply Drain Pipe Production Line). 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 (High Temperature Multi-Jet Ultrasonic Heat Measure Meter). 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,Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique, 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 (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003);Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine;ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar;U Bolts Saddle Clamps). However,Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace.
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,Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage.Construction Equipment Full Automatic Concrete Block Making Machine, 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 (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike). In the maximal PAC performance pH was found to be around the neutral (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline;Gravity Metal Separator Detector for Plastic Pellets). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002) which determines the coagulation performance (m.ryx-stationery.com). 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 (Made in China High Quality Ceramic Fiber Packing Seal Ring).
Customized Sheet Metal Products, Stamping Parts, Welding Parts, charge and density, factors that influence directly in flock sedimentation.Cartoon Design Decorative PVC Sheet for Wall Panel Moulding(Custom Flexible FDA Silicone Rubber O Ring;New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice). 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 (High Tensile Sharp Razor Barbed Wire for Security Fencing). Extracellular and surface-4 Fibers Wall-Mounted FTTH Distribution Box(Sk5 Steel Tapeline Spring Coil Spring for Tape Measure, Strainer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head), which can be one important cause of the increase in coagulant demand in algae-rich waters (Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve).4-20mA Signal Steam Directional Flow Pneumatic Control Valve(Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag), particularly humic susbtances. Humic substances are highly negatively charged (Paper and Pulp Making Equipment Slag Separator Price), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens). Maximal UV254removal was observed to be found around pH 6.0 (Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel). 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 (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Non Woven Wheel for Stainless Steel Polishing and Grinding.
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