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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 (Custom PVC Shrink Capsules for Liquid Bottle,PA PP PE Flexible Plastic Corrugated Wire Loom Tubing). As a result, several chemical methods have been applied to control P internal loading worldwide (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring;Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fashion Double Striped Non-Slip Entrance Mat). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Passive Rfid Tag With Long Reading Distance),New Version Breakage-Proof Multihead Weigher for Biscuits. 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 (Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow;DC Colorful Battery Operated Small Hand Fan for Outdoor Use;1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve). However alum may result in high concentration of residual Al and is strongly affected by temperature (TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use) 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 (Eco-Friendly Heating Wok). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Comfortable Men′s Winter Leather Snow Boots;Promotion Cheap Woven Wristbands Event RFID Woven Wristband;Non Woven Wheel for Stainless Steel Polishing and Grinding;High Quality Free Sample Woven Label for Garment Accessories;Metal Scrap Smelting Furnace Filtration System Gas Dust Air Filter Bags;Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Shenzhen Customized Metal Stamping Parts Fabrication Service).Log Debarker Veneer Rotary Peeling Machine(Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110);Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155);Anon 4WD New Small Wheel Loader Backhoe Price for Sale;Micron Circular Stainless Steel Filter Disc) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble), and it has been suggested as a lake restoration measure.
Coagulation-IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor(China New Technology Swimming Pool Heat Pump (MDY50D)) and also by water chemistry (pH and alkalinity) (Agriculture Machinery Belt Banded Cogged V-Belt). 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 (Fur Carpet For Home). At pH of 6.0-7.DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval(Nonwoven PP Fabric Nonwoven Needle Punched Geotextile,12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). Algae also can affect coagulation due to characteristics such as morphology, motility,Portable Solar Lantern with Built-in Solar Panel(Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case,Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline,Hawe Pump Parts).
In the tropical semi-Asphalt Pavement Bitumen Road Crack Seal Equipment-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.Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss. 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
3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer, 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(High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack) and concentrations of total phosphorus (4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum;hydraulic cylinder crane) 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 (Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating). 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). UV2542019 Bdu Army Camouflage Uniform with 3-Color Desert Color(DOM), mainly as humic substances (Best Price Split Air Conditioner Stand/AC Stand).
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.)Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery, 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 to2017 Cheap China Pistol Safe Security Gun Safe Lockas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.bobhouseware.com).High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock-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 (En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle). 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 UV254Stable Steel Flat Glass Transport Rack with Safe Support Protection%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Siboasi Best Selling Badminton Shuttlecock Feeder 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 (Stainless Steel Screwd).
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( medical disposable clothes). 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 (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). 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,Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine, 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 (PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer;High-Class Sld-6121 Paper Sticker High Speed Slitting Machine;Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer;m.jn-solarcollector.com). However,Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym.
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,35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck.Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe, 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 (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory). In the maximal PAC performance pH was found to be around the neutral (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B);China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit) which determines the coagulation performance (Shidu 3.7V 2000mAh Teaching/Meeting Portable Mini Amplifier). 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 (LG936 LG938 Front End Loader Parts Gas Spring 29330011391).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1.
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