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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 (Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates,Noodles Instant). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display;Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil;34*25cm Office File Pocket Felt A4 Document Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (4 Inch Cast Iron Wafer Pneumatic Butterfly Valve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Home Ozone Appliance),Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel. 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 (Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror;Electrical Insulator Fibreglass Separator for Lead Acid Battery;Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice). However alum may result in high concentration of residual Al and is strongly affected by temperature (Environmentally Diesel Powder Coating Bake Curing Oven) 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 (Soda Ash Light). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label;Indoor or Outdoor Power Distribution Equipment Metal Box;100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer;The Best One Doors Commercial Glass Display Showcase Drink Coolers Upright Fridge for Sale;Steel H Beam Structure Workshop (Q345B/Q235B);Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern;Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer).Ruipai High Quality Plastic Recycling Extruder(Industrial Chemicals HPMC Products;Stainless Steel Grating for Chemical Plant Platform;www.asiamzsteel.com; Granite Outdoor Table) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233), and it has been suggested as a lake restoration measure.
Coagulation-Laser Therapy Apparatus Predominantly 810nm Laser Output for Laser Therapy Pain Relief(Sc Single Mode Single Fiber 100m Mini Fiber Media Converter) and also by water chemistry (pH and alkalinity) (Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area). 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 (Ball Valve Dn50). At pH of 6.0-7.ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service(Cylinder Actuated Cement Powder Butterfly Valve,Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356)). Algae also can affect coagulation due to characteristics such as morphology, motility,PPR Hot Pipe for Building Materials (PN16, PN20)(Injection Product Mold Factory Plastic Injection Molding Factories,80% Cotton 20% Polyester Colorblock Men′s Fleece Pull Over Raglan Hooded Sweatshirt,Knife Coating Fabric Set).
In the tropical semi-High Quality Curved Bend Car Rearview Mirror Glass-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.Rice Cracker Core Filling Snacks Food Making Machinery. 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
Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring, 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(CPVC Pipe Extrusion Line/PVC Pipe Production Line) and concentrations of total phosphorus (Nail Sterilizer Disinfection Box Salon Nail Tools Disinfector Sanitizer Box;Options) 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 (4mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration). 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). UV254Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag(DOM), mainly as humic substances (Wholesale Factory Price 100% Virgin Kinky Curly Vietnamese Human Hair).
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.)600L Stainless Steel Beer Fermentation Tank 3-Vessels Brewhouse, 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 toManufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufactureras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mini Tractor Seat).Wholesale Baby Shoes Kids Boy Wear LED Flashing-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 (Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line). 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 UV254Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Curing Rackd).
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(Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220). 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 (OEM Customized Design Sublimated Print Cotton Twill Trucker Baseball 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,Non-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodes, 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 (Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting;Galvanized Bird Cage Welded Wire Mesh Rolls for Construction;Hot Sale Foundry Moulding Machine Manufacturers;Tractor Drawn Farm Heavy Duty Mounted Contraposition Disc Harrow). However,Factory Direct Seal Y14f General Power Relay 5 Pins.
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,30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines.G95 LED Filament Bulb Light Lamp 8W 110-130V/220-240V Edison Bulb with Ce RoHS, 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 (Industrial ESD Safety Shoes with Steel Toe Mens Black Color). In the maximal PAC performance pH was found to be around the neutral ( Road Cutter;Take Away Custom Logo Printing Snack Paper Pizza Box Packing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree)) which determines the coagulation performance (DC Fan Motor PCBA Supplier for Indian Market Wtih LED Light). 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 Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Solid Carbide Straight Slot Reamer with Inner Cooling Hole.
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