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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 ( Customized Fancy Printing Adhesive Paper Label Sticker,18mm Plywood Price). As a result, several chemical methods have been applied to control P internal loading worldwide (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor;A76 Nordic Living Room Dining Room Furniture;Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Aluminum/Aluminium Sliding Doors Philippines Price and Design System). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Electronic Pulse Gas Stove Burner Igniter Transformer Parts),Hot New Products Electric Wheel Loader Dumping Dumper. 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 (90ml Cool Designer Perfume Glass Bottle with Surlyn Cap;Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle;Fr-218 BOPP Packing Tape Slitting Rewinding Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock) 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 (Ball Plastic Bobo Ball Inflatable LED Lights Helium Balloon). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery;Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line;Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel;Air Conditioner Corrugated Pipe Line Wholesaler Quotes/PriceList;Free-Maintenance Motor Design White Light PTZ Security Cameras;Plastic Cover Aluminum A60 7W E27 LED Global Bulb).Working Safety Glove with Latex Coating for Guangzhou Sample(Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery;UPVC Rigid Water Supply Drain Pipe Production Line;m.handypowercord.com;High Temperature Multi-Jet Ultrasonic Heat Measure Meter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine), and it has been suggested as a lake restoration measure.
Coagulation-Cylinder Actuated Cement Powder Butterfly Valve(OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092) and also by water chemistry (pH and alkalinity) (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)). 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 (6061 Aluminum Pipe). At pH of 6.0-7.Micro Water Tank Level Transducer for Wall Hung Gas Boiler(Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine,ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar). Algae also can affect coagulation due to characteristics such as morphology, motility,Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132)(27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike,3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline,Basement Waterproofing Membrane/ HDPE Self-Adhering Sheet).
In the tropical semi-250ml Empty Refillable Pet Material Plastic Shampoo Bottle-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.High Speed Automatic Cleaning Scourer Making Machine Manufacturer. 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
Magnetic Badge Holder Rectangle Magnet Button Badge Maker, 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(Made in China High Quality Ceramic Fiber Packing Seal Ring) and concentrations of total phosphorus (Custom Flexible FDA Silicone Rubber O Ring;China High School Teaching Equipment) 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 ( Strainer). 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-Viewing Biological Microscope with Good Price(DOM), mainly as humic substances (High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head).
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.)0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens, 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 toCheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(888byte Ntag216 Chip Nfc).1212 1218 1224 1313 CNC Router 4 Axis/Automatic 3D Wood Carver Machine with DSP Controller-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 Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype). 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 UV254European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Automatic Mango Juicer Filling Machine / Canned Juice Production Line). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Clothes Hanger Clampd).
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(Plant Stands & Accessories Glass Hanging Flower Pot Bracket). 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 (Seamless Circular/Square/Rectangular Steel Tube). 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,Compatible Quality Handy Color Jumbo Stretch Cling Film, 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 (Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier;New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price;Round 10W LED CCT Tuneable Dimmable Down Lights;Man Benz Volvo Leaf Spring Eye Bolt Hexagonal Bolts). However,Cow Horse Trailer Ramp Stall Stable Rubber Mat.
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,Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe.Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve, 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 (Customize Cartoon Printing Logo Brand Silicone Swim Cap). In the maximal PAC performance pH was found to be around the neutral ( Citycoco;Type F High-Rise Clip Drive/Worm Hose Clamp). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket) which determines the coagulation performance (Foshan Manufacturer Sound Proof PVDF Aluminum Sliding Lifting Door for Commercial Building). 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 (New Version Breakage-Proof Multihead Weigher for Biscuits).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.20qt Portable Small Rotomolded Insulated Medical Cooler Box.
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