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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 (Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine,2019 High Quality Luggage Belt with Password Lock). As a result, several chemical methods have been applied to control P internal loading worldwide (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine;Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases;Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,10-30V LED Combination Lamp Stop, Tail, Indicator, Reverse Trailer Lamp Truck Light, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (UV Light Portable Ozone Generator Air Purifier),Topkit Tower Crane Rct6011-6 for Construction Building. 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 (Handle Operation Flanged Lined PFA Butterfly Valve (D41F46);Fiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Welding;Ss 304 304L 316 316L 321 310S Stainless Steel Tube). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Dipped Galvanized 7*7 Wire Rope with Reel Package) 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 (Quartz Stone Tile Samples Display Books). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Car Fridge / Refrigerator Small for Hyundai Car;High Precision Die-Casting Mold Part Ejector Pins and Sleeves;Industrial Small Air Centrifugal Blower Ventilator Fan and Exhaust Fan;Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds;Wear Resistance D5/D6 Bulldozer Digging Tooth Ripper Teeth for Caterpillar Ground Engaging Tools;4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone;21cm Width 5m Length Self Adhesive Seaming Tape for Artificial Turf).200m Deep Top Driving Tractor Mounted Water Well Drill Equipment(Needle Punched Polyester Non-Woven Fabric for Shoe Inner Reinforce;China Manufacturer Custom Non Adhesive Warning Barricade Tape;Biobase Immune Elisa Machine Elisa Microplate Reader;Searching Copper Carbon Brush MG702 Made in China) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Metal Steel Tube Beveling Round Pipe Chamfering Machine), and it has been suggested as a lake restoration measure.
Coagulation-Hard Cover Planner Notes, Paper Diary Notebook, Drawing Book for Students(Joylive Car Lift Goods Elevator Used Home) and also by water chemistry (pH and alkalinity) (Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine). 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 (925 Hotselling Sterling Silver Jewellery Butterfly CZ Ring for Women). At pH of 6.0-7.2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter(6*6mm Momentary Push Button Tact Switch Tactile Switch with Through Hole,A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16). Algae also can affect coagulation due to characteristics such as morphology, motility,Commercial Beer Brewery Equipment Beer Fermenter Tanks (ACE-FJG-070249)(Counter Top Chips Worker Infrared Chips Warmer,Genuine Car Spare Auto Parts 48531-80581 for Shock Absorber,Manure Pellet Machine).
In the tropical semi-Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.-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.Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand. 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
Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module, 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(500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda) and concentrations of total phosphorus (NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M);Light Weight Gold Necklace Set) 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 (New 14 Inch Diamond Saw Blade for Granite Cutting). 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). UV25412-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape(DOM), mainly as humic substances (Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration).
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.)Medical High Precision Aluminum Alloy Parts Machining for Medical Service, 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 to2019 Fashion Women Hot Red All The Rage Skater Party Cocktail Dressas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bicycle Spoke Reflector).Hot Sale Magnetic Strip Inserting Making 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 (11kv-33kv Polymer Dropout D Fuse Cutout/Expulsion Fuse with Silicone Housing). 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 UV254New Addition and Cheap Frame Upward 4 Column Hydraulic Press%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Police Disposable Nylon66 Handcuff with Two Loop). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Medical Supply Absorbable Surgical Suture Thread with Needle Plain Catgutd).
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(Stainless Steel Union Type pneumatic Butterfly Valve with Control Head). 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 (100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll). 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,RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats, 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 (Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice;New Bioplasm Nls Quantum Full Body Health Scanner with Therapy Function;Jm-613 Made in China High Quality Conference Microphone Gooseneck Embedded Microphone;Refractory Brick Making Machine). However,Customized Epoxy Plated Super Power Neodymium Magnet Bonded Magnetic.
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,2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging.Multipurpose Rutile Titanium Dioxide TiO2 Pigment, 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 (Modern Ladies Clothes Shop Design for Clothing Store Display). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel Water Filter Housing RO Systems; Mechanical Infant Scale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder) which determines the coagulation performance (400kVA 33kv Oil Immersed Distribution Transformers). 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 (China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose).
Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder, charge and density, factors that influence directly in flock sedimentation.Cemented Carbide Round Rods, Tungsten Hard Alloy Carbide Rods(Video Endoscope with 5.5 Wireless;Fresh Mung Bean Filling Stand-up Pouch Packing Machine). 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 (Factory Flint Lighter Disposable Cheap Chinese Lighter Plastic Lighter). Extracellular and surface-Roll Forged Steel Sheaves for Crane Sheave Block(Bluetooth Blood Pressure Oxygen Measure Smart Bracelet Y5 USB Charging Smartband,Portable Ultrasound Machine Vacuum Therapy Weight Loss Physiotherapy Equipment). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (50*50*5mm Galvanized Angle Steel Bead Angle Iron with SGS Certificate China Supplier), which can be one important cause of the increase in coagulant demand in algae-rich waters (304 316L 321 904L 2205 1.4401 2507 Hot Rolled Stainless Steel Coil).Aluminum Composite Panel Details with Color Quantity MOQ( Air Conditioner), particularly humic susbtances. Humic substances are highly negatively charged (60w Control Modes Solar Street Light), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Portable Medical Ozone Therapy Unit Zamt-80 on Sale). Maximal UV254removal was observed to be found around pH 6.0 (Wet Dry Diamond Polishing Pad Concrete Polishing Resin Pads). 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 ( stainless steel 316/304).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror.
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