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 (Mimaki SB210 Dye Sublimation Ink for TX400-1800D Inkjet Printer,Dx51d Z100 Hot Dipped Galvanized Steel Coil for Corrugated Roofing Sheet). As a result, several chemical methods have been applied to control P internal loading worldwide (Exchange Table Plate Round Square Metal Fiber Laser Tube Cutting Machines;630kgs Galvanized Suspended Platform;Schedule 40 Stainless Steel 304L Pipe and Tube). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Auto Parts Engine Cooling Air Conditioner OEM 88450-26120). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Black PU Auto Car Neck Rest Car Seat Headrest Neck Pillow, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Concrete Mixer 750l),Receipt Book/Invoice Book/Business Form Book. 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 (New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring;100W/150W/200W Industrial High Bay UFO LED for Tennis Court Lighting;Eeto Laser Metal Sheet Fiber CNC Laser Cutting Machine Price). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Cheap Cattle / Field Fencing) 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 (gentian violet). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Bimetal Bushing Composite Oilless Bush Sliding Bearing Bush;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;30ml Glass E Liquid Bottles;Install High Density Hardie Ceiling Tile Fiber Cement Board;Magic Mirror Facial Skin Analyzer / 3D Face Camera).Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machine(Cement Grout Pump Grouting Machine Price Concrete Grouting Machines;Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery;Custom Electrostatic Metallic Powder Paint;Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Brass Component Auto Parts Medical Equipment CNC Machining), and it has been suggested as a lake restoration measure.
Coagulation-Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat(Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear) and also by water chemistry (pH and alkalinity) (Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center). 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 (Dia. 3mm Laser Small Aspheric Lens for Laers Focus). At pH of 6.0-7.Standard Vertical Rotary Automated Smart Tower Car Parking System(Outdoor Decoration Small Music Dancing Garden Water Feature Fountain,Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope). Algae also can affect coagulation due to characteristics such as morphology, motility,Stainless Steel Water Filter Housing RO Systems(Economical Wall Decoration PVC 3D Brick Wallpaper Designs,1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector,Ipl Rf E Light Cavitation Beauty Machine).
In the tropical semi-Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP-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.Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots. 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
PVC Shrink Sleeve for Glass Bottle Capsule, Shrink Wine Cap, 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(LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens) and concentrations of total phosphorus (Swivel Hook Auto Engine Valve Spring Motor Spring;Cat Scratcher Board) 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 (Galvanized Pullet Chicken Cage Baby Chicken Cages). 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). UV254Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt(DOM), mainly as humic substances (Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light).
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.)Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen, 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 toAutomatic Vertical Grain / Sugar / Bean / Rice Packing Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(FSC FDA 14-27GSM Hand Rolling Paper Made in China).Textile Machine Parts Multiple Pattern Box-aand total phosphorus concentrations.
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 Rectangular Pipes for Balcony Guardrail). 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 UV2542020 Sale Stuffed Meatball Processing Meat Ball Making Machinery%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Modified Shipping Container House for New Zealand). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Promotional Enamel Teapotd).
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC). 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 (Socket Type 2 32A 22kw EV Charging Point EV Charger for Electric Vehicle Charging). 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).
4. Discussion
In general,94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent, 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 (Absorbent PP Mat Hardwearing Doormat with Round Shape;China Wholesale Hydraulic Industrial Winch for Mining Well;LPG Gasification Pressure Regulating Skid in Mobile Station Building;Igs Fish Hunter Fish Shooting Game Machine with Plush Chassis). However,Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System.
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,Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e.106cm TV Background Decorative Wallpaper China Design, 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 (3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler). In the maximal PAC performance pH was found to be around the neutral (Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling;Fashionable New Products Twin Screw Extruder for Pet Recycling). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (5/8 Inch Stainless Steel Banding in Plastic Tote) which determines the coagulation performance (High Quality CEO Working Executive Office Desk (SZ-ODL301)). 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 (Electric Rail Transport Wagon Warehouse Transfer Vehicle).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration.