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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 (The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture,2019 New-Tech Thin Wet-Punching Tail-End Card Metallic Card Clothing Wire). As a result, several chemical methods have been applied to control P internal loading worldwide (DIN7504 Stainless Steel Self Drilling Drywall Screw; Construction Pipes Price;Synthetic Filament Spunbonded and Needlepunched Nonwoven Geotextiles). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (DIY Modern Metal Wine Bottle Rack Organizer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fiber Yarn Type Fiberglass Drywall Self-Adhesive Joint Tape for Construction),Woodworking Edition - Waxed Canvas Tool Bag - Padded Straps. 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 (Circular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1;3-Wheel Motorcycle with 1500W Motor and EEC Certificate;10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor) 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 (25w Led Track Light High Quality Supplier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Patient Modular Monitor with Wireless Network and Wire Network;25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake;Medical Infusion Pump for Human and Veterinary with Fluid Warmer;Ce Certificated Acm-60 PTFE Powder Grinding Mill;E Car Charger;Buildings Materials ASA PVC Roof Tile Roofing Sheet;Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging).Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter(Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall);Auto Crane Electrical Overhead Cable with Steel Wire;Funny Separate Heart-Shaped Pink Plush Toy Pillow;Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer), and it has been suggested as a lake restoration measure.
Coagulation-Six Spout Impeller Cement Packing Machine(Reflecting Aluminum Film Vacuum Evaporation Coating Equipment) and also by water chemistry (pH and alkalinity) (5mm Wall Mounted Hotel LED Lighted Bathroom Mirror). 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 (a-topmachine.com). At pH of 6.0-7.One-Stop Condensing/Compressor/Refrigeration Unit Freezer Cold Store(Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings,China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine(Airstream Mobile Food Truck Trailer/ BBQ Food Caravan/ Beverage Cart,Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine,Cnc Machine Milling And Turning).
In the tropical semi-6*6mm Momentary Push Button Tact Switch Tactile Switch with Through Hole-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.8PCS*10W RGBW LED Spider Moving Head Beam Stage Light. 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
Wd190V Handheld Metal Detector Gold Metal Detector Made in China, 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(3D Silver Reflective Custom Heat Transfer Label Garment Label) and concentrations of total phosphorus (Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove;Glass Fiber Raw Materials Good Insulation Fiberglass Yarn Industrial Yarn) 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 (Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers). 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). UV254Factory Wholesale Price Fingerprint Access Control with TCP/IP and WiFi(DOM), mainly as humic substances (Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags).
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.)DC/Ec Inverter Motor Ceiling Horizontal Type Fan Coil Unit, 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 toJL 155cm Life-Size Real Perfect Asian Shemale Sex Doll Torso for Manas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Olebr Solar Power Bank).Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim-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 (Industrial Coal Fired 8 MW Hot Water Boiler Factory Price). 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 UV2541325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Heat Insulation and Fireproof Composite Sandwich Wall Panel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Eyeshadow Case Packagingd).
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(China Supply Soft and Hard 304 316 Stainless Steel Wire Hot Sale in Amazon). 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 (Carbon Fiber Composite Autoclave Pressure Vessel for Sale). 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,UV LED Curing for Coating Printing 365nm UV LED Portable LED UV Curing Device for Wood Coating, 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 (High Elastic Nylon Breathable Arm Elbow Sleeve for Sports;Silicone Hand Pipe Hand Tobacco Pipes Smoking Pipe with Glass Bowl;AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars;Outdoor Slim 50W 100W 200W SMD LED Floodlighting). However,China Factory Price 6 Axles Tractor Truck Trailer.
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,2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7).304, 316 Slot Stainless Steel Tube with Glass, 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 (Hot Sale Low Price Small IGBT Magnetic Induction 40kg Steel Scrap Melting Furnace for Metal Melting). In the maximal PAC performance pH was found to be around the neutral (28dBi 1575.42MHz BNC Connector Active GPS Antenna;Electric Vehicle Brushless DC Motor 3kw 1500rpm 48V). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Fully Automatic Frozen French Fries Making Machinery Manufacturer Price) which determines the coagulation performance (Customized Brass Spur Gear with Precision Machining). 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 ( Product Label).
Giant Christmas Socks Carnival Amusement Park Inflatable Slide, charge and density, factors that influence directly in flock sedimentation.Multifunction Massage Rainfall Shower Column with Five Functions(China Supplier Fresh Milk Tank Delivery Truck for Farm Use;Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (DC 12V 24V Mini Portable Camping Car Freezer for Car). Extracellular and surface-Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller(304 316L Polished Finished Stainless Steel Tubing with ISO Standard,30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Quality CEO Working Executive Office Desk (SZ-ODL301)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line).Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative(Customized Silicone Rubber O-Ring Seal Sealing Housing Gasket), particularly humic susbtances. Humic substances are highly negatively charged (CNC Aluminum 5052 6061 7075 Milling Auto Spare Parts Car / Components), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (How a Gravity Belt Thickener Works Thickening or Dewatering). Maximal UV254removal was observed to be found around pH 6.0 (Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Custom Printed Sublimation Printing Fit Yoga Pants Leggings).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Easywell & Minston Electric Platform Scale with Height Meter BS-200lp.
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