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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 (WPC Wall Cladding Waterproof Exterior Wall Panels,18 Inch Ball). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Best Price Portable and Oprional Steam Generator Sauna;Replacement LCD Digitizer for Apple iPhone 6plus;Aluminum Tamper Evident Droppers with Insert Dropper for Glass Bottles). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Bearing Accessories Bearing Ball Bearing Rollers). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Sale MID-Temperature Commercial Dehydrator Large Capacity for Nuts, Fruit&Vegetable, Meat Drying, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cheapest Price Modular Turf Protection Flooring Soccer and Football Artificial),Empty Toner Lotion Pump Glass Bottle Cosmetic Bottles. 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 (Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet;Top Quality Precision Floor Industrial 2 Ton Weighing Scale;Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration). However alum may result in high concentration of residual Al and is strongly affected by temperature (Luxury Black Color Shower Door and Shower Enclosure (MB-226)) 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 Hex Socket Head Bolt). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery;Small Playground Plastic Slide Preschool Equipment Toys for Kids;Solid Carbide Straight Slot Reamer with Inner Cooling Hole;2.5m Commercial Combined Island Display Showcase Freezer for Supermarket;Brass Fitting;Solid Surface Grade Grinding Alumina Tyihydrate;LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture).THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC(45 Degree Copper Pipe Joint in Air Conditioner;Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid;6-Strand Chemical Fiber Ropes Mooring Rope PP Rope Polyester Rope PE Rope;High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hydra Diamond Microdermabrasion Peel Facial Machines), and it has been suggested as a lake restoration measure.
Coagulation-Long Service Life Smooth Lead Screw Tr3.5X0.61(Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence) and also by water chemistry (pH and alkalinity) (New Arrivel Grand Sale Wholesale Soft Fishing Lure). 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 (10.76mm 11.14mm 11.52mm Clear Laminated Glass Tempered Glass Polished Edge). At pH of 6.0-7.Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall(Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group,Manufacturer Woven Patches and Customized Woven Badge). Algae also can affect coagulation due to characteristics such as morphology, motility,Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal(Provide Low-Volume Production Injection Moulding,Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank,Customized Security Cigarette Label).
In the tropical semi-Must 4kw 2HP Pump Power Inverter Ags Bts Available-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.Food Cardboard Paper Packing Box for Pastry. 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
1390 Mixed CO2 Laser Cutting Machine for Wood Acrylic MDF Stainless Steel Carbon Steel Plywood Cut, 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(18000CMH Portable Commercial Industrial Evaporative Mobile Water Air Cooler) and concentrations of total phosphorus (Lab Paddle Blender/Stomacher Blender /Sterile Homogenizer;Stainless Exhaust Clamp Engine for Butt Joint Band Set Accessory) 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 (1.0L Chinese Steam Cooking Type Electric Tea Kettle with Pot). 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). UV254Water Heater Single Head Shrinking Machine(DOM), mainly as humic substances (Stainless Steel Extruder Screen Packs/Filter Screen Packs/Circular Mesh Screen).
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.)Discount HOWO High Pressure LPG Delivery Dispenser Truck, 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 toAirplane Used Super Soft U Shape Memory Foam Neck Travel Pillowas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(12v Lithium 100ah).Ldd-100 High Efficient Electric DTH Drilling 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 (Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories). 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 UV254Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Urea Cover U Shape Electric Heated Smart Toilet Bidet Seat). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Density MTP-LC Cassetted).
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(Horizontal Semi Auto Tie Hydraulic Press/Pressing Baler). 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 (OEM Custom Plastic Injection Mold for Mobile Phone Case). 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,Ss 304 304L 316 316L 321 310S Stainless Steel Tube, 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 ( Miner Lamp;Structural Materials ERW Black Steel Pipe for Construction;Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone;API 610 Standard Bb4 Centrifugal Multistage High Pressure Boiler Feed Water Pump for Power Plants). However,Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop.
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,Hydraulic Press Machine Oil Press for Metal Deep Drawing Press.Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride, 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 (Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag). In the maximal PAC performance pH was found to be around the neutral (Continuous 1-4 Lines Cij Batch Number Automatic Industrial Inkjet Printer;Butterfly Valves with Lever Handle Top Quality Factory PVC Valve). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle) which determines the coagulation performance (Baritone Ukulele). 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 (OEM Hardware Factory Custom Fabrication CNC Aluminum Signet).
Custom Engraved 2D Metal Volleyball Medals, charge and density, factors that influence directly in flock sedimentation.Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair(12L Ice Chest Ice Bucket Plastic Cooler Box;Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%). 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 (Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing). Extracellular and surface-VGA multi screen video wall LCD video wall panel with wall screen matrix(Custom Logo Printed Brown Shopping Bag,High Speed Spiral Dough Mixers 50kg Flour for Bread). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting), which can be one important cause of the increase in coagulant demand in algae-rich waters (Full Automatic Sachet Cartoning Pack Machine (ZH100)).16oz Pet Plastic Food Jar with Embossed Metal Lid (PPC-PJ-1701)(Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm), particularly humic susbtances. Humic substances are highly negatively charged (PVC Coated Galvanized Iron Wire), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Waterborne Epoxy Resin for Waterborne Epoxy Coatings). Maximal UV254removal was observed to be found around pH 6.0 (Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair). 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 (Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Filtration Small Size Large Processing Capacity Bag Filter.
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