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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 (Factory Directly Ss 304 Stainless Steel Toilet Cubicle Fitting Indicator Latches,Rubber Gloves). As a result, several chemical methods have been applied to control P internal loading worldwide (New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9;CPVC Pipe Extrusion Line/PVC Pipe Production Line;Nail Sterilizer Disinfection Box Salon Nail Tools Disinfector Sanitizer Box). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wall Mounted Air Purifier Ozone Generator for Home/Office, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Safety Edge Switch for Automated Guided Vehicle Agv),Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick. 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 (Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box;4mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration;Wholesale Factory Price 100% Virgin Kinky Curly Vietnamese Human Hair). However alum may result in high concentration of residual Al and is strongly affected by temperature (up-Down Table 1390 100W CO2 CNC Laser Cutter Machines) 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 (China 3/16 4.763mm Ss316 G100). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality for Kawasaki K3sp36 Replacement Parts;High Quality Firefighting Rescue Equipment Safety Rescue Tripod;Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer;Great Quality Waste Water Treatment Polyaluminium Chloride PAC;800mm China Automatic Drainage Construction Tunnel Boring Machine;I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds;Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line).Purchase Covered with PVC Creamy Durability Kitchen Cabinets Furniture(Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging Machine;Building Lifting Equipment Trolley Electric Cable Winch;China Pellet Machinery;Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (OEM Customized Design Sublimated Print Cotton Twill Trucker Baseball Cap), and it has been suggested as a lake restoration measure.
Coagulation-Triangle Plastic Checkout Counter Divider Bar with Logo Printed(Factory Direct Price Automatic Snack / Candy Grain Packing Machine) and also by water chemistry (pH and alkalinity) (Manufactured Goods PPGI Coil Corrugated Steel Sheet). 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 (100% Polyester High Visibility Reflective Rainbow Fabric for Clothing). At pH of 6.0-7.Agricultural Machinery Partslinear Bearings Kh3050(Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting,Galvanized Bird Cage Welded Wire Mesh Rolls for Construction). Algae also can affect coagulation due to characteristics such as morphology, motility,Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle(Hot Sale Foundry Moulding Machine Manufacturers,Industrial ESD Safety Shoes with Steel Toe Mens Black Color,FM USB Radio Audio Power Amplifier for Home Bar Club).
In the tropical semi-Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)-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.Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine. 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
Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip, 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(1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree)) and concentrations of total phosphorus (New Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer;White Color High Efficiency Exhalation Valve Activated Dust Mask Air Pollution Disposable) 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 (Sesame Almond Cashew Nut Peanut Butter Making Processing Machine). 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). UV254Free Sample From Factory High Quality White Kaolin Clay Price(DOM), mainly as humic substances (En10305 Cold Drawn/Rolled Seamless Steel Tube for Hydraulic Tube).
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.)0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal, 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 to6061 6063 Extrude Aluminum Extrusion Profile Section Supplieras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Panel Edge Bonding Machine).Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label-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 (Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer). 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 UV2548.8ah, High Production Efficiency Skateboard%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Foshan Manufacturer Bathroom Glass Sliding Door Roller). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4kw Single Phase Electric Motord).
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(SGS Certificate PE Heat Shrink Film for Beer). 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 (Sandblast Finish Inside Glass Lampshade with Rod Different Colors Are Available). 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,Smart Electronic RoHS Weighing Scale PCB Manufacturer with Fast Delivery, 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 (FDA Natural Banish Hangovers Dihydromyricetin (DHM) 98% HPLC;Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang Machine;Automatic Disposable Hotel Supplies Packing Machine Horiaontal Wrapping Machine;Long Life Gardner Denver Air Compressor Oil Filter Cartridge). However,12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools.
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,Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover.Stainless Steel Extruder Screen Packs/Filter Screen Packs/Circular Mesh 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 (Stainless Steel Sheet 254smo). In the maximal PAC performance pH was found to be around the neutral (40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale;China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth) which determines the coagulation performance (Fashion Travel Luggage Bag Trolley Case Set Suitcase). 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 (Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail).
Optical Solar Smoke Detector with Testing Button (ES-T601), charge and density, factors that influence directly in flock sedimentation.Steel Wire, Security Protected Razor Barbed Wire/Blade Barbed Wire(Organic Fertilizer Production Line for Manure Treatment;Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand). 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 (Android Data Cable Mobile Phone USB Cable Mobile Phone Cables). Extracellular and surface-Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush(China Filler Masterbatch Machine Wholesaler,High Chrome Cast Iron Mud Sand Slurry Pump Parts). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( VDE), which can be one important cause of the increase in coagulant demand in algae-rich waters (Pet Strap Production Line with Good Quality).Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine(XCMG Official 150 Ton Rough Terrain Crane Rt150), particularly humic susbtances. Humic substances are highly negatively charged (Apply to Metso Nordberg Gp220 Single Cylinder Cone Crusher Spare Parts Lower Thrust Bearing), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Factory Direct Sale Baseball Uniform for Adults). Maximal UV254removal was observed to be found around pH 6.0 (Red Color Garage Matting Rubber Sheet Flooring Manufacture in China). 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 (Laser Cutting Machine 500W 1000W 2000W Fiber Laser Pipe and Tube Cutting Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic White Cardboard Paper Roll to Sheet Cutting Machine.
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