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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 (Metal Building Industrial Shed/Pre-Engineered Long-Span Steel Structure Frame Building,Ms Steel Pipe). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt;1.0L Chinese Steam Cooking Type Electric Tea Kettle with Pot;Stainless Steel Extruder Screen Packs/Filter Screen Packs/Circular Mesh Screen). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Industry Grade Tct Circular Saw Blades for Cutting Aluminium). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Life Size Rubber Penis Dildo),Hot Sale Outdoor Car Carport Shelter with Low Price. 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 (China Foshan Good Quality Chalk Black White Board;90 Degree Over Molding Black Audio and Video Cable Edgarcn 306;Airplane Used Super Soft U Shape Memory Foam Neck Travel Pillow). However alum may result in high concentration of residual Al and is strongly affected by temperature (Digital 8 Channel Tinnitus-Masking Programmable Powerful BTE Hearing Aid) 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 (6063 6082 High Hardness Aluminum Pipe Aluminum Alloy Pipe). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Beautiful Design Wholesale Empty UV Gel Nail Polish Bottle;Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories;Urea Cover U Shape Electric Heated Smart Toilet Bidet Seat;76mm Garden Hose Fittings Straight Reducing;Cheap PriceList for Useful Liquid Organic Fertilizer With High Phosphorus - Double Shaft Chain Fertilizer Crusher - Exceed ;Horizontal Semi Auto Tie Hydraulic Press/Pressing Baler;OEM Custom Plastic Injection Mold for Mobile Phone Case).Golf Ball Pick-up Ball Retriever Ball Scoop Telescopic up to 5.5m(Power Electric Diesel Generator 200kVA Chinese Manufacturers and Suppliers of Generators;120W Foldable Mono Crystalline Solar Panel PV Module Battery Power System Amazon OEM;Good Quality High Safety Footwear Factory OEM/ODM Products; Miner Lamp) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Structural Materials ERW Black Steel Pipe for Construction), and it has been suggested as a lake restoration measure.
Coagulation-Collagen Wound Dressing Plug for Teeth Extraction(Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone) and also by water chemistry (pH and alkalinity) (Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag). 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 (China Factory Clomid Raw Material Powder with Good Quality). At pH of 6.0-7.2017 Cheap China Pistol Safe Security Gun Safe Lock(Continuous 1-4 Lines Cij Batch Number Automatic Industrial Inkjet Printer,Butterfly Valves with Lever Handle Top Quality Factory PVC Valve). Algae also can affect coagulation due to characteristics such as morphology, motility,10ml Plastic and Glass Small Travel Perfume Bottle(Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle,OEM Hardware Factory Custom Fabrication CNC Aluminum Signet,China Three Axles Semi-Trailer).
In the tropical semi-Gravity Metal Separator Detector for Plastic Pellets-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.High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building. 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
Galvanized Cast Iron Floor Sow Farrowing Crates with Piglets Nursery Crates, 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(Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing) and concentrations of total phosphorus (High Speed Spiral Dough Mixers 50kg Flour for Bread;10inch Schedule 40 Carbon Steel ERW Pipe Casing for Water/Well with Black Painting) 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 (Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm). 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). UV254SRS Painting Green Color 10ml Thick Glass Roller Ball Bottle(DOM), mainly as humic substances (Waterborne Epoxy Resin for Waterborne Epoxy Coatings).
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.)Automatic Food Canning Machine Tin Can Vauum Seamer, 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 toOuter Side Mirror Left and Right Rearview Mirror for Skodaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cheap Wholesale 2cc Cup Capacity Special Nails Art Airbrush).Circular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1-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 (Constant Temperature Hot Water Machine Swimming Pool Heat Pump). 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 UV254Small Camping Inflatable Roof Tent with Strut%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PVC Water Pipe Fittings Plastic Flexible Hose Price Rubber Hosed).
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(LDPE Plastic Garbage Bags for Construction Wastes). 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 (15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts). 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,Multi-Function Voltage Current Test Tool LCD LED Backlight Tester, 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 (Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice;Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt;New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project;Hpgr Carbide Part). However,Professional Korea Hifu Focused Ultrasonic Beauty Machine for Wrinkle Removal.
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,LCL Consolidation Shipping Freight From Guangzhou to Dayton, Oh.Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover, 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 (Wholesale Sport Wear Mens Gym Running Polyester T Shirt). In the maximal PAC performance pH was found to be around the neutral (Compatible Physio Control 11996-000033 NIBP Hose;Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom PVC Shrink Capsules for Liquid Bottle) which determines the coagulation performance (Forestry Garden Harvester Timber Grip Grab Bucket for Mini Digger). 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 (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring).
Injection Product Mold Factory Plastic Injection Molding Factories, charge and density, factors that influence directly in flock sedimentation.Kaishan YT23D Forging Air Leg Support Rock Drill Machine(Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench). 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 (Fashion Double Striped Non-Slip Entrance Mat). Extracellular and surface-factory outlet excellent herbicide DIURON 80% WDG on sale(Direct Black Apb High Quality Supplier,Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (DC Colorful Battery Operated Small Hand Fan for Outdoor Use), which can be one important cause of the increase in coagulant demand in algae-rich waters (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve).Water Park Outdoor Playground with Water Spray Device for Sale(TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use), particularly humic susbtances. Humic substances are highly negatively charged (Wholesale Whale SPA Pedicure Chair with Full Function Massage/Salon Beauty Chair/Pedicure Bench), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Wholesale Comfortable Men′s Winter Leather Snow Boots). Maximal UV254removal was observed to be found around pH 6.0 (Promotion Cheap Woven Wristbands Event RFID Woven Wristband). 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 (Non Woven Wheel for Stainless Steel Polishing and Grinding).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Precision Self-Aligning Roller Bearing 1219.
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