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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 Mining Equipment with Drawing Design,Stainless Steel Sintered Powder Candle Filter for Oil Removal). As a result, several chemical methods have been applied to control P internal loading worldwide ( Motor Cable Wire Electrical Power Cable;Class 1 Foam Rubber Insulation Pipe for Air Conditioner;Sublimation Coated Aluminum Sheets for Heat Transfer Printing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Welded Stainless Steel Tube 321),Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home. 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 (Ccaf Vertical Cartridge Dust Collection for Sand Blasting; Camping;GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture) 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 (Hansel Shopping Mall Coin Operated Moving Animal Kids Rides). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim;Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong; Flour Mill Machine;Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown;White Marble / Black Marble Mosaic Tile / Pattern/Special Design Tile;Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc;Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser).Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack( Restaurant Kitchen Used Lift;Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging;Marble Pattern PE/PVDF ACP Use Color Coating Colorful Aluminium Composite Panel;2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Beautiful Design Coral Fleece Terry Towel Set), and it has been suggested as a lake restoration measure.
Coagulation-Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring(Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber) and also by water chemistry (pH and alkalinity) (Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36). 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 (Sheep Race Panels). At pH of 6.0-7.Seamless Circular/Square/Rectangular Steel Tube(Genuine 1m USB Date Charging Cable for iPhone,Filter Fiber Car Engine Cabin Air Filter for Mazda). Algae also can affect coagulation due to characteristics such as morphology, motility,Construction Equipment 1.5 Cube Materials Portable Concrete Mixer( Customized Available,Vulcanized Fiber Paper Electrical Insulation Paper,Fiber Laser Metal Engraving Machine Aluminum Laser Marking Printing Machine).
In the tropical semi-Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler-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.Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing. 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
Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch, 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(Double Station Pesticide HDPE Bottle Making Machine) and concentrations of total phosphorus (Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels;Aluminum Machining Casting Parts for Auto Parts) 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 (M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports). 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). UV2542018 Hot Selling Gold Stainless Steel High Bar Chair(DOM), mainly as humic substances (Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm).
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.)High Precision Ultrasonic Vibro Screen for Refractory Material Separating, 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 toOnline pH TDS Ec Controller Digital Electrical Conductivity Meteras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Trailer/Truck Brake Shoe for Truck Part Eaton805678/805679 4317).Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent-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 ( Wood Peeling Lathe). 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 UV254Banana Slicer Cutter Perfect for Fruit Salad Yellow Banana Cutting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2019 New Arrival Original Adaptive Fast Adapter Rapid Wall Charger for Samsung S10). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cheap Water Resistant Fresh Oak Luxury Vinyl Plank Flooringd).
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(7inch TFT LCD Display Module for Car Compass with resolution 1024(RGB)*600). 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 (Smart Access Control RFID NFC Epoxy Crystal Tag Card). 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,Blocking-Concealed Passport Holder RFID Wallet with Neck Strap, 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 (Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light;1500 W /2000 W Disabled Electric Tricycle with Double Seat;China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm);Ferrite Ring Speaker Magnet). However,Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233.
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,Luau Pinhole Glasses Promotional Sunglasses Yiwu Market (B3030).Professional Fabrication Metal Sheet Mechanical Stamping Machine Parts, 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 (Pneumatic Ef Series Air Preparation Units Filter). In the maximal PAC performance pH was found to be around the neutral (3600 Rpm Concrete Machinery Ride on Power Trowel Factory;Concrete Grinding Plate for Abrasive Machines of Abrasive Disc). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (5 pins grey black blue plastic connector straight plug INT- PAG. M0.5GL. AC52A/G/J/N/R/V/B) which determines the coagulation performance (Rake Mount). 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 (Expert Supplier Of Stainless Steel Electric Cooking Pot).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Full Automatic Egg Tray Manufacturing Machine.
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