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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 (Exchange Table Plate Round Square Metal Fiber Laser Tube Cutting Machines,12000w Uninterrupted Power Supply). As a result, several chemical methods have been applied to control P internal loading worldwide (630kgs Galvanized Suspended Platform;Schedule 40 Stainless Steel 304L Pipe and Tube;Auto Parts Engine Cooling Air Conditioner OEM 88450-26120). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PE PP LDPE LLDPE Agriculture Film Recycling Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Electrical Far Infrared Ceramic Lamp Heater Black and White Color),DIN6915 Ss 316 304 Stainless Steel High Tensile Hexagon Nut with Bolt for Structural Bolting. 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 (100W/150W/200W Industrial High Bay UFO LED for Tennis Court Lighting;Eeto Laser Metal Sheet Fiber CNC Laser Cutting Machine Price; Cheap Cattle / Field Fencing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Bimetal Bushing Composite Oilless Bush Sliding Bearing Bush) 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 (P2.97 Low Power Consumption Indoor Curved LED Display for Hanging / Stacking Panel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (PU Foam CNC Circular Contour Sponge Cutting Machinery/EPE Cutting Machine;HRC60 4 Flutes Corner Radius Solid Carbide Cutting Tools End Mill;Industrial Automatic High Quality PVC Fast Speed Roller Shutter;Install High Density Hardie Ceiling Tile Fiber Cement Board;3g Router With Sim Slot;Magic Mirror Facial Skin Analyzer / 3D Face Camera;Cement Grout Pump Grouting Machine Price Concrete Grouting Machines).SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer(Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery;Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved;Elbow Double Beveling Machine With Automatic Control;Brass Component Auto Parts Medical Equipment CNC Machining) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear), and it has been suggested as a lake restoration measure.
Coagulation-Double Arm Medical Pendant for Anesthesia (HFP-DS240/380)(Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center) and also by water chemistry (pH and alkalinity) (Outdoor Decoration Small Music Dancing Garden Water Feature Fountain). 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 (100cm Mini Silicone Sex Doll Lifelike Love Doll). At pH of 6.0-7.Disposable Take out Paper Food Salad Sushi Lunch Box Container(Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope,Economical Wall Decoration PVC 3D Brick Wallpaper Designs). Algae also can affect coagulation due to characteristics such as morphology, motility,CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist(1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector,DFAC High Altitude Operation Platform Truck 10m for Sale,Body Tight T Shirts).
In the tropical semi-Newest Hot Sales Metal 360 Degree Reading Glasses with Case-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.Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock. 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
Carbide 4 Flutes HRC60 Blue Coated Milling Cutters, 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(Swivel Hook Auto Engine Valve Spring Motor Spring) and concentrations of total phosphorus ( Security Protected Razor Barbed Wire/Blade Barbed Wire;Wind Turbine Tower Transport Semi-Trailer/Transportation for Wind Turbine/Trcuk Trailer) 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 (Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light). 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). UV254120W Foldable Mono Crystalline Solar Panel PV Module Battery Power System Amazon OEM(DOM), mainly as humic substances (CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories).
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.)Safety Disposable Shoe Cover for Lab Visitor, 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 toIP65 8W Outdoor Integrated LED Street Light Solar Lampsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Dual Frequency RFID Access Card).Aluminum Hard Equipment Gift Flight Case for Guitar-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 (Modified Shipping Container House for New Zealand). 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 Quality Wooden Cabinet Design Shoe Display Unit for Shop%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (coffee bag factoryd).
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(Socket Type 2 32A 22kw EV Charging Point EV Charger for Electric Vehicle Charging). 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 (Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door). 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,Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine, 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 (China Wholesale Hydraulic Industrial Winch for Mining Well;LPG Gasification Pressure Regulating Skid in Mobile Station Building;3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler;Bottom Entry Mixer). However,High Speed Disposable Lunch Box Egg Tray Making Forming Machine.
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,2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door.Buildings Materials ASA PVC Roof Tile Roofing Sheet, 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 (Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling). In the maximal PAC performance pH was found to be around the neutral (Fashionable New Products Twin Screw Extruder for Pet Recycling;5/8 Inch Stainless Steel Banding in Plastic Tote). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Electric Rail Transport Wagon Warehouse Transfer Vehicle) which determines the coagulation performance (www.vtimejewelry.com). 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 (Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.China Metal Cooling Fan for Dry-Type Transformer.
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