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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 (Littlefuse IC Fuse Cartridge Ceramic Electronic Component Nanosmdc012f-2,Good Quality Galvanized Umbrealla Head Roofing Nails). As a result, several chemical methods have been applied to control P internal loading worldwide ( AC4900ca;Carbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washers;Waterproof Antislip PVC S Mat PVC Z Mat for Bath Swimming Pool Factory Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Steel Drilling Water Well Filter / Bridge Slot Screen Pipe). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (360 Degree Panoramic 2.0MP WiFi Smart Home Bulb IP Camera),35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck. 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 (Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars;C-Type 2 Piece Tin Can Making Punch Press Machine;Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control) 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 (Fashion Hot Sale Tortoise Shell Sunglasses). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom Ductile Iron Casting Parts Gray Iron Sand Casting;High Quality Sand Paper for Sand Machine Brush (YY-170);Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu;Engineering Plastic Material;Airless Shot Blast Cleaning Machine;SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings;GMP Certified Collagen Softgel for Fish Collagen).Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe(26000lm 200W LED High Bay Lamp Fixture for Gym House Factory;Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor;High Quality Best Price Hardcover Customized Book Printing;Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Corn Starch Foam Biodegradable Frozen Food Packaging Tray), and it has been suggested as a lake restoration measure.
Coagulation-Fertilizer Binder and Dispersant Sodium Lignin Sulfonate(Good Quality of 60t/D Wheat Flour Milling Plant) and also by water chemistry (pH and alkalinity) (Energy Saving One Step Automatic Tritan Pet Blow Molding 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 (Pre-Insulated Steel Pipe Polyurethane Foam Insulation and HDPE Jacket). At pH of 6.0-7.Reducer Hydraulic Fitting with Swivel Nut (2D)(Bailian F Customized Server 2019 Hot Sell IPTV Server,100-400V DC Input Without Battery System 10000W 3 Phase Output Power Inverters with Solar Prority). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable(Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts,Potato Chips Design Non-Toxic Silicone Baby Teether Toy,Name: Single Orifice Automatic Air Valves,Flanged End1.Standard: Conforms to BS EN1074-4:20002.Flange drilled to EN1092-23.Material: Ductile Iron4.Normal Pressure:PN10/165.Size: DN40-DN200).
In the tropical semi-Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine-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.UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1. 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
Bright Polished Galvanzied Common Iron Wire Nails, 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(OEM Stamping Parts Aluminum Profile Stamping for Child Safety Seats) and concentrations of total phosphorus (Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine;Supply Automatic Tissue Paper Napkin Machine and Slitting Rewinding Machinery) 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 (Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment). 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). UV254Factory Direct Price Automatic Snack / Candy Grain Packing Machine(DOM), mainly as humic substances (Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field).
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.)Online pH TDS Ec Controller Digital Electrical Conductivity Meter, 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 toExdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Manufacturer High Quality Garage Door SUS 304 Tension Spring).Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon-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 (Best Industrial Coal Fired Steam Boiler Manufacturer in China). 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 UV254V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Steel Pneumatic Automatic Car Chassis Number DOT Peen Marking 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(Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin). 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 (Monofilament Fishing Tackle Green Nylon Fish Net). 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,How a Gravity Belt Thickener Works Thickening or Dewatering, 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 (High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line;1000kg/Day Ice Making Machines Custom Ice Cube Machine;CNC OEM ODM Customized Car Housing Parts Machining Parts;Resort Tent Dome). However,Wholesale MIG Stainless Steel Welding Wire Soldering Wire Super Quality Welding Wire.
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,1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree).Best Plastic Water Bottle 750ml Tritan Drinking Bottle, 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 (Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen). In the maximal PAC performance pH was found to be around the neutral (Sports Bra Shock-Proof Gathering Stereotypes Bra;2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Stainless Steel Mesh Screen Automatic Self-Cleaning Filter) which determines the coagulation performance (Professional Anti-Slip Trampoline Socks for Trampoline Park with Different Sizes). 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 (Hot Sale 250ml Green Dorica Glass Olive Oil Bottle).
Recessed Colorful Solar Interaction LED Underground Lighting, charge and density, factors that influence directly in flock sedimentation.FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body(7;Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer). 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 (High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide). Extracellular and surface-Industrial Air Cooled Heat Pump Water Chiller in Many Field(Customized Metal Casting Mechanical Machine Parts with Powder Coating,Round Vibrating Separator Machine - Round Vibratory Sieve). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (600ml Travel Sports Bicycle Water Bottle (HBT-037)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Shielded Mini Ball Bearings with Anti-Rusty Stainless Steel Smr106zz).Building Material Colorful Stone Coated Metal Spanish Roofing Tile(OEM Aluminum Housing Fuel Filter Housing for Truck/Train Parts), particularly humic susbtances. Humic substances are highly negatively charged (Tungsten Tig Welding Rod), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014)). Maximal UV254removal was observed to be found around pH 6.0 (Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems). 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 (Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid.
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