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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 (Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts,Arc Gouging Carbon Graphite Electrode Products Made in China). As a result, several chemical methods have been applied to control P internal loading worldwide (SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer;Chocolate High Speed Automatic Feeding and Packing Line;Antitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Label). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Discount HOWO High Pressure LPG Delivery Dispenser Truck). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Welded Wire Mesh BBQ Grill Grate/Mesh for Cooking, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (150x150 Steel Square Pipe Manufacturers Cheap Price),Tp321 Stainless Steel Coil Tube for ASTM A269. 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 (Precision CNC Machined Part Aluminum Stainless Steel Components;Building Material Stone Tile Full Body Marble Porcelain Tile; 5.0mm Disk). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Speed Four Shafts Auto Exchange BOPP Tape Cutting Machine) 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 (High Quality Double Shielded Bare Copper 2 Cores Microphone Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Push up Breast Enlargement Bra SGS Test Certificate Backless Adhesive Silicone Bra Transparent;Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts;Updated Stylish Peristaltic Biogas Pump Gas Booster Pump;Rapid Test Pregnancy HCG Test Strip Ce&ISO&SABS Certificate;Txk Portable Crane 1500 Kg Permanent Magnetic Lifter;Ss Wire Mesh Heat Resistant Wire Mesh Conveyor Belt;Cosmetic Raw Materials 3-O-Ethyl Ascorbyl Ether Powder CAS 86404-04-8).Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032)(Hot New Kids Machine High Quality Self-Control Cat Mechanical Parts Swing Carnival Rides for Sale;W/B Block-out Fabric Sublimation Textiles for Backdrop with Black Coating;Cr Coil;OEM High Efficiency Polycrystalline 260W Solar Panel) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality of Glassware Bottle of Essential Oil Reed Diffuser Perfume), and it has been suggested as a lake restoration measure.
Coagulation-Chinese Manufacturer Quality Magnetic Filter Drawer Separator(Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet) and also by water chemistry (pH and alkalinity) (36W/48W Interchangeable AC DC Adapter Free Samples 14 Years Experience). 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 (Korloy Spmr120308-M Nc3030 Milling Insert for Milling Tool Carbide Insert). At pH of 6.0-7.2.0mm Pitch Pin Header SMT Type R Sereis Single Row Dual Housing(Durable Building Construction 3 Ton Hoisting Electric Winch for Sale,Renewable Biodegradable Stand up Pouch Coffee Manufacturer in China). Algae also can affect coagulation due to characteristics such as morphology, motility,2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price(PVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rolls,NEMA 17 0.9/1.8 Degree Two Phase Electric Step Stepper Motor with Permanent Magnet Brake,Stainless Steel 205 Non-Magnetic Well Screens).
In the tropical semi-High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution-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.Tamper Evident Walmart Office Depot White out Warning Void Self-Adhesive Security Tape for Bottle. 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
Long Range RFID Access Control Card for Non-Stop Parking, 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(Fused Silica Flange with High Temperature Resistance) and concentrations of total phosphorus (Brake Light Rear View Camera for Fiat Ducato;Professional Multi Gym Exercise Equipment Hammer Strength Power Cage Half Rack) 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 (GRP FRP Fiberglass Composite Epoxy Resin Water Treatment Pipe Tube Cylinder). 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). UV254Magic Smart Bluetooth Illuminated Mirror Bathroom LED Mirror with Clock Display(DOM), mainly as humic substances (Personalized Heat Transfer Printing Plastic Ice Bucket Beer Champagne Cooler).
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.)Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1), 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 toSchedule 40 Stainless Steel 304L Pipe and Tubeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Coronavirus Rapid Testing Kit).6 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine-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 (100W/150W/200W Industrial High Bay UFO LED for Tennis Court Lighting). 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 UV25476mm Garden Hose Fittings Straight Reducing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Eeto Laser Metal Sheet Fiber CNC Laser Cutting Machine Price). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (growookd).
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(Bimetal Bushing Composite Oilless Bush Sliding Bearing Bush). 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 (PU Foam CNC Circular Contour Sponge Cutting Machinery/EPE Cutting Machine). 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,Yuanchen Nonwoven Needle Punched PPS Filter Felt, 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 (Install High Density Hardie Ceiling Tile Fiber Cement Board;Magic Mirror Facial Skin Analyzer / 3D Face Camera;Cement Grout Pump Grouting Machine Price Concrete Grouting Machines;Full Stainless Steel Tomato Sauce Processing Machine/Sauce Processing Machinery). However,Gear Box Forged Steel Bw Ends Full Welded Ball Valve.
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,Engineering Plastic Material, Nylon/PA Sheet.Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging, 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 (Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery). In the maximal PAC performance pH was found to be around the neutral (Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved;Brass Component Auto Parts Medical Equipment CNC Machining). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear) which determines the coagulation performance (750 GSM Needle Felt High Temperature Air Filter Bag PTFE Fabric). 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 (Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center).
Heated Lunch Box/ Food Insulation Plastic Box/Heat Preservation Plastic Box, charge and density, factors that influence directly in flock sedimentation.Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile(Outdoor Decoration Small Music Dancing Garden Water Feature Fountain;Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope). 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 (Economical Wall Decoration PVC 3D Brick Wallpaper Designs). Extracellular and surface-500ml Amber Pharmaceutical Glass Bottle Medicine Bottle Chemical Bottle Pesticide Bottle(1060 Aluminum Sheets,1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (DFAC High Altitude Operation Platform Truck 10m for Sale), which can be one important cause of the increase in coagulant demand in algae-rich waters (Y Series 315 Case High Power 75kw 90kw 110kw 132kw 6-Pole Three-Phase AC Motor).Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile(LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens), particularly humic susbtances. Humic substances are highly negatively charged (Amber and Black Finish), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Swivel Hook Auto Engine Valve Spring Motor Spring). Maximal UV254removal was observed to be found around pH 6.0 ( Security Protected Razor Barbed Wire/Blade Barbed Wire). 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 (Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless.
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