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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 (Spot Supply Al2O3 85% Bauxite Use for Calcined,1J0820803B compressor). As a result, several chemical methods have been applied to control P internal loading worldwide (Industrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabric;High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle;304 Stainless Steel Deep Drawn Parts for Kitchen Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Indoor Commercial Economical Outdoor Public Heavy Duty Passenger Elevator Escalator (XNFT-001), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Iron Bushings),Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu. 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 (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo;Optical Fiber Cable MTP/MPO Cassette for Data Center;High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging). However alum may result in high concentration of residual Al and is strongly affected by temperature (Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720) 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 (Good Price 20t Gasoline Wood Log Splitter). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve;High quality 110V DC Power Supply for American Market;Best Polystyrene Sandwich Board Manufacturer;High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping;Steel Seamless Pipes;Customized Microfiber Sport Towel for Swimming Towel;Customized Small Module Sintered Metal Product Spur Gear Pinion).Eco Friendly Kraft Biodegradable 5ml Bamboo Lip Balm Tubes Lipstick Tube(Wg9130583017 Sino Truck Spare Parts Combination Switch;Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag;2.4 Inch Lcd;Waterproof Magnesium Oxide False PVC Ceiling Panel) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron), and it has been suggested as a lake restoration measure.
Coagulation-Uncoated Test Liner Fluting Medium Paper for Box Packaging(Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33)) and also by water chemistry (pH and alkalinity) (Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261). 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 (Home Furniture Living Room Fabric Recliner 3 Seater Sofa). At pH of 6.0-7.Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price(Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data,High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off). Algae also can affect coagulation due to characteristics such as morphology, motility,High Density Multi-Layer PCB Prototype PCB Printed Circuit Board Professional Manufacturer(Aluminum Height Adjustable Walking Cane (SC-CR58-67),Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e,Rubber Wood Bread Bin And Drawer).
In the tropical semi-2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch-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.Low Price & High Quality Stainless Steel X-ray Lead Door. 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
Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt, 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(Home Security Video Door Phone Camera Doorbell Intercom System for Villa) and concentrations of total phosphorus (White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem;High Quality Plastic Slat Floor for Pig/Poultry/Goat/Duck Farm-Free Sample) 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 (5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD). 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). UV254High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals(DOM), mainly as humic substances (AAC Block Making Machine Line Supplier/AAC Block Machinery).
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.)Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor, 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 toa-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style aas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Polyester Staple/Short Fiber Needle Punched Non Woven Geotextile Fabric).PVC Stripe Anti-Slip Door Mat with Color Logo-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 (4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System). 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 UV254Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hot Runner High Precision Plastic Injection Mold for Household Home Appliance). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.worldlinkhat.comd).
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(Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes). 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 (2018 Hot Selling Gold Stainless Steel High Bar Chair). 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,Personal Skin Care Silicone Sonic Facial Cleansing Brush, 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 (Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench;Strong Block Permanent NdFeB Magnet for Motor Application;New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds;IN-700 Medical Portable USB Air Compressor HRV Heat Recovery Ventilator). However,Environmental Shot Peening Machine with Less Dust Emission, Model: Mrt2-80L2-4.
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,Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine.19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen, 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 ( Telehandler Price). In the maximal PAC performance pH was found to be around the neutral (Automatic Pesticide Bottle Blowing/Making Machine;ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining) which determines the coagulation performance (Remote Control Arm/Disarm/Unlock/Lock Car GPS Tracker Central Lock). 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 (High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread.
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