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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 (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle,Grinding Ball For Autogenous Mill). As a result, several chemical methods have been applied to control P internal loading worldwide (Fr-218 BOPP Packing Tape Slitting Rewinding Machine;Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manufacture Leather Strap Japan Movt Stainless Steel Back Watch (cm19092), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Best Led Light Bluetooth Speaker),Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder. 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 (Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line;Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel;Free-Maintenance Motor Design White Light PTZ Security Cameras). However alum may result in high concentration of residual Al and is strongly affected by temperature (Plastic Cover Aluminum A60 7W E27 LED Global Bulb) 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 (Preseasoned Cast Iron Cookware). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery;UPVC Rigid Water Supply Drain Pipe Production Line;High Temperature Multi-Jet Ultrasonic Heat Measure Meter;Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine;Hidden Video Camera Child;OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092;Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)).Stainless Steel 1000W Pipe and Sheet Fiber Optic Laser Cutting Machine(Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine;ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar;Rechargeable LED Rave Glasses/Sound Reactive Equalizer Lights LED Glasses with USB Charger;27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline), and it has been suggested as a lake restoration measure.
Coagulation-High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling(Gravity Metal Separator Detector for Plastic Pellets) and also by water chemistry (pH and alkalinity) (Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002). 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 (Inner Ear Loop Disposable Face Mask Making Machine). At pH of 6.0-7.Pneumatic Rubber Wheel for Wheelbarrow 4.10/3.50-4(Made in China High Quality Ceramic Fiber Packing Seal Ring,Custom Flexible FDA Silicone Rubber O Ring). Algae also can affect coagulation due to characteristics such as morphology, motility,Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine(New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice,High Tensile Sharp Razor Barbed Wire for Security Fencing,China compounding pelletizing line).
In the tropical semi-Chubont Hot Selling Waterproof Duffel Trolley Bag Size 19/22 Inch-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.Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming. 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
Top Quality Cleaning Cloth Microfiber Hair Salon Towel, 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(Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve) and concentrations of total phosphorus (Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag;m.oytmachinery.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 (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace). 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). UV254Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve(DOM), mainly as humic substances (Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven).
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.)2 Ton Brand New Small Cheap Backhoe Loader for Sale, 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 toPlant Stands & Accessories Glass Hanging Flower Pot Bracketas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(90 Degree Bevel Helical Transmission Gearbox).Middle Duty 20 Discs Harrow for 50 HP Tractor-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 (Lightweight New Design Girl Fashion Bags Children School Backpack). 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 UV254OEM Custom Precision CNC Machined Steel Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Acetic Anhydride 3d Modeld).
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(Round 10W LED CCT Tuneable Dimmable Down Lights). 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 (Customize Cartoon Printing Logo Brand Silicone Swim Cap). 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,Seamless Steel Tube ASTM A335 P11, High Temperature Boiler Steel Pipe Tube ASME SA335 P22 P 91, 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 (28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket;New Version Breakage-Proof Multihead Weigher for Biscuits;S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer;Sigle Line Siomay Machine). However,Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness.
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,Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance.Stainless Steel 4.8/8.8/10.9 Galvanized Non-Standard/Machine/Auto Parts/Spare Parts Screw, 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 (FDA Approved Custom Eye Mask Packaging Bag / Mylar Foil Facial Mask Pouch / Cosmetic Cream Sachet). In the maximal PAC performance pH was found to be around the neutral (European Type 7 Pin 13 Pin 12V 24V Brass Contact Truck Vehicle Trailer Plug Socket;Zumex Style Speed Tank Podium Commercial Citrus Juicer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (CNC Metal Fiber 2000W Laser Cutter with Switching Working Table) which determines the coagulation performance (Packing Machine of Cutting Machine on-Line Jc-EPE-Qd1750 Automatic for EPE Foam Sheet/Film). 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 (Unistrut Type Slotted Steel Strut Channel or C Channel).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center.
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