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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 (27.5er Sram 12speed carbon Mountain Bike with Air Suspension Fork,Antomatic Integrated Plate And Shell Heat Exchanger Unit). As a result, several chemical methods have been applied to control P internal loading worldwide (Ce Approved Gobal Warranty 200kVA 100kVA 50kVA 25kVA Diesel Generator Price;Aluminum/Aluminium Foil/Coil for Retort Pouch/Bag/Stand-up Pouch A8079/1235/8011-Soft 5.9/6 Microns;High Purity Medical Psa Oxygen Generator/Concentrator Manufacurer with Low Cost). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (925 Fashion Silver Jewelry with Zircon Set Ring Wholesale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Egyptian Made Furniture),MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration. 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 (Full Automatic Egg Tray Manufacturing Machine;Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs;High Speed HDMI to HDMI Cable 1.4 Version 1080P 3D Standard 2.0). However alum may result in high concentration of residual Al and is strongly affected by temperature (LPG Filling Station (Volume Optional) Gas Station with Dispenser Mobile LPG Skid Mounted) 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 (12v Mini Dc Motor Water Pump). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts;19′′ Smart Table Android Windows PC Touch Screen Kiosk;High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos;Hot Selling Construction Machine 50cbm/H Ready Mixed Concrete Mixing Plant;Oat Bar Machine;Metal Enclosure Withdrawable Distribution Switchgear Cabinet Low Voltage;Individually Wrapped Paper Straws Compostable Paper Drinking Straws).Sf606 Serve Motor Automatic Wood Cut off Saw Machine(10ml Plastic and Glass Small Travel Perfume Bottle;Factory Price 1100 Aluminum Disc Discs Circle Round Plate;Outdoor Camping Sleeping Bag Envelop Sleeping Bag for Adult;Bsg-901 High Quality Cheap Price Soccer Goal Nets) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Galvanized Steel Concrete Nail Use for Construction), and it has been suggested as a lake restoration measure.
Coagulation-Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer(Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing) and also by water chemistry (pH and alkalinity) (Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel). 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 (Bathroom Accessories Rainfall Shower Head Set System Brass Chrome Bath & Shower). At pH of 6.0-7.Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)(Shanghai Port Adjustable Steel Hinge for Security Wooden Door,Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches(PLC Control Multi Layer Rubber Tile Plate Vulcanizer,Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup,Standard Size Shower Room).
In the tropical semi-Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil-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.13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card. 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
ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee, 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(Healong Company Customized Soccer Jersey for Club) and concentrations of total phosphorus (Poultry Farming Equipment Chicken Cage for close farming house Automatic design;Audience Election Equipment Suppliers for Sale) 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 (Car Parts Best Price Ik22 5310 Iridium Spark Plugs). 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). UV254Farrowing Crate Galvanized Swine Farrowing Crates(DOM), mainly as humic substances (Chinese Manufacturer Quality Magnetic Filter Drawer Separator).
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.)Double Sided Tape 1/2 Inch 10 Feet, Transparent Acrylic Double-Sided Tape, 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 toOscillating Knife Cutter for Car Seat Coversas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(30rpm 300rpm Low-Speed 42mm Automatic Sliding Door High-Torque DC Planetary Gear Brushless Motor).Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog-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 (Wholesale 7.2X4.5X4.7m Christmas Inflatable Santa Bouncer with Slide). 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 UV254High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (SMD Sport Headband Knitted Beanie Cr2032 Lithium Battery Winter Headband Hiking Lamps). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Commercial Cube Ice Machined).
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(Cooling Water Chemicals Scale Inhibitor and Corrosion Inhibitor for Power Plant). 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 (Men′s Watch High Quality Steel Quartz Wrist Watch (72057)). 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,Health Food Krill Oil Softgel for Antioxidation, 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 (Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS;Ce Certificate Factory Price Food Grade Type Pressure Level Sensor;Excellent Performance EPE Foam Sheet Making Machine;Black Hdpe Corrugated Pipe Machinery Suppliers/Manufacturers for Sale). However,Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe.
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,Custom Sport Event Antique Brass Plated Lanyard Available Medal.Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker, 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 (Hospital All Kind of Adult Child Old Man Disposable SpO2 Sensor). In the maximal PAC performance pH was found to be around the neutral (Factory Price Rotary 1530 4 Axis CNC Router for Promotion;Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (61539 Double Handle 4 Inch South American Style Faucet) which determines the coagulation performance (Mens Oversized T Shirt T Shirt Men 100% Cotton Digital T-Shirt Printing Machine). 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 (3 Axle 50-80t Cimc Low Bed Trailer Lowboy Semi Trailer Trcuk Tractor Trailer).
4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale, charge and density, factors that influence directly in flock sedimentation.Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra(Us Type Drop Forged Self Colored Shoulder Eye Bolt;Four Color Printing Gloss Art Paper Hardcover Book). 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 (Environmental Luminescent White Light Glow in The Dark Powder Pigment). Extracellular and surface-Factory Manufacture Clear and Brown BOPP Packaging Tape(Sealing Tape,7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator), which can be one important cause of the increase in coagulant demand in algae-rich waters (Electric Convection Bread Bakery Oven Made in China).2019 New Product 12mm Mini Short Metal Push Button Switch(Biogas Digester Double Membrane Gas Holder Anaerobic Fermentation Tank), particularly humic susbtances. Humic substances are highly negatively charged (Ductile Iron Body), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Chemshun Y-Shape Pipe Liner Used in Iron and Steel Manufactueres). Maximal UV254removal was observed to be found around pH 6.0 (Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine). 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 (Disposable Polypropylene Protective Head Wear Bouffant Cap).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ae Bifacial Solar PV Panel 270W Poly German Quality.
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