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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 (Building Material Stone Tile Full Body Marble Porcelain Tile,SGCC Galvalume Aluzic Steel Coil Gl Steel for Roofing Sheet). As a result, several chemical methods have been applied to control P internal loading worldwide ( 5.0mm Disk;High Speed Four Shafts Auto Exchange BOPP Tape Cutting Machine;Push up Breast Enlargement Bra SGS Test Certificate Backless Adhesive Silicone Bra Transparent). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Longboard or Skateboard Ball Bearings 608zz 608-2RS, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Baby Safety Products),Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather. 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 (Updated Stylish Peristaltic Biogas Pump Gas Booster Pump;Rapid Test Pregnancy HCG Test Strip Ce&ISO&SABS Certificate;Ss Wire Mesh Heat Resistant Wire Mesh Conveyor Belt). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cosmetic Raw Materials 3-O-Ethyl Ascorbyl Ether Powder CAS 86404-04-8) 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 (Casting Steel Grinding Resistant Ball Supplier & Manufacturer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot New Kids Machine High Quality Self-Control Cat Mechanical Parts Swing Carnival Rides for Sale;W/B Block-out Fabric Sublimation Textiles for Backdrop with Black Coating;OEM High Efficiency Polycrystalline 260W Solar Panel;High Quality of Glassware Bottle of Essential Oil Reed Diffuser Perfume;Industrial Mini Electricity Portable Screw Air Compressor;Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet;36W/48W Interchangeable AC DC Adapter Free Samples 14 Years Experience).Metal Steel Tube Beveling Round Pipe Chamfering Machine(Durable Building Construction 3 Ton Hoisting Electric Winch for Sale;Renewable Biodegradable Stand up Pouch Coffee Manufacturer in China;Sodium Hydroxide Tank Semi-Trailer 3 Axles 20000liters;PVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rolls) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (NEMA 17 0.9/1.8 Degree Two Phase Electric Step Stepper Motor with Permanent Magnet Brake), and it has been suggested as a lake restoration measure.
Coagulation-Individually Wrapped Paper Straws Compostable Paper Drinking Straws(Promotion 100%Cotton Baseball Cap Manufacturer Export to Europe) and also by water chemistry (pH and alkalinity) (Auto Parts Nitril Rubber Bellows with Competitive Price). 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 (Square Cooling Tower). At pH of 6.0-7.Flanges Male Female Fittings Assembled with Flexible Metal Hose(Fused Silica Flange with High Temperature Resistance,Brake Light Rear View Camera for Fiat Ducato). Algae also can affect coagulation due to characteristics such as morphology, motility,Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller(Js500 Twin-Shaft Concrete Mixer for Block Machine,China Construction Machinery Sheet Metal Parts Manufacturers CNC Auto Parts,Erikc Copper Gasket Washer Bosch F00vc17504 (F 00V C17 504) Brass Pressure Washer F00V C17 504).
In the tropical semi-Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment-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.Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm. 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
Automatic 2 Color Screen Printing Machine for Bottle Lids with UV Curing System, 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(Mimaki SB210 Dye Sublimation Ink for TX400-1800D Inkjet Printer) and concentrations of total phosphorus (Exchange Table Plate Round Square Metal Fiber Laser Tube Cutting Machines;High Pressure Above Ground Swimming Pool Electric 380V Water Pumps) 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 (Auto Parts Engine Cooling Air Conditioner OEM 88450-26120). 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). UV254Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire(DOM), mainly as humic substances (New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring).
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.)Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine, 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 toBimetal Bushing Composite Oilless Bush Sliding Bearing Bushas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hotel Supplies Towel Manufacturers Cheap Price).Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price-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 (Industrial Automatic High Quality PVC Fast Speed Roller Shutter). 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 UV254Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Install High Density Hardie Ceiling Tile Fiber Cement Board). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2.4g Wireless Sync Dimmerd).
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(Cement Grout Pump Grouting Machine Price Concrete Grouting Machines). 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 (Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery). 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,Large Size Double Flange Rubber Lined Butterfly Valve with Worm Gear Operated, 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 (Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear;Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center;Outdoor Decoration Small Music Dancing Garden Water Feature Fountain;Autamatic Feeding Cutting Machine). However,Perfect Protection for Guideways of Stainless Steel Telescopic Way.
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,High Precision Machinery Plastic Parts with Injection Mold.Kynko Li-ion Cordless Drill with 18V Battery (KD30), 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 (Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope). In the maximal PAC performance pH was found to be around the neutral (Economical Wall Decoration PVC 3D Brick Wallpaper Designs;1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (DFAC High Altitude Operation Platform Truck 10m for Sale) which determines the coagulation performance (Cjx9 Seires Air Condition Definite Purpose AC Magnetic Contactor). 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 (Y Series 315 Case High Power 75kw 90kw 110kw 132kw 6-Pole Three-Phase AC Motor).
304 Stainless Steel Pipe Manufacture in China, charge and density, factors that influence directly in flock sedimentation.3D Finish Soundproof Movable Partition Wall for Meeting Room(LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens;Swivel Hook Auto Engine Valve Spring Motor Spring). 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 ( Security Protected Razor Barbed Wire/Blade Barbed Wire). Extracellular and surface-1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale(ASTM 53 1 1/2 Inch Price Per Meter Galvanized Steel Pipe/Tube,Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Galvanized Pullet Chicken Cage Baby Chicken Cages), which can be one important cause of the increase in coagulant demand in algae-rich waters (Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light).Nr, EPDM Rubber Buffer for Auto, Machinery, Air Conditioner(CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories), particularly humic susbtances. Humic substances are highly negatively charged (Sheet Metal Fabrication), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment). Maximal UV254removal was observed to be found around pH 6.0 (Sheet Metal Stamping Galvanized Steel Panel and Frame). 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 (Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality 11oz Bone China Color Change Mugs Sublimation Coating Mugs (Matte).
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