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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 (Waterproof Spunbonded Flame Retardant Fabric for Function Textile,3d Metal Nail Decoration Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000;Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate;Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (10kw 20kw 30kw 50kw Small Gas Generator for Home Use). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Manufactory Hotel Pillow Synthetic Polyester Microfiber Down Alternative Cushion),Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging Machine. 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 (Fastener Screw /Self Tapping Screw / Machine Screw;Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper;Plastic Cable Electric Plug Making Machines Supplier). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel) 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 (Fiberglass Clarifier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner;Multifunction Massage Rainfall Shower Column with Five Functions;Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings;20PCS Porcelain Dinnerware with Popular New Design;Acquisto della macchina per la rimozione della ruggine laser;Electric Control Polystyrene Cuttrt EPS Block Cutting Machine;Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516)).Panic/Emergency Button/Switch for Alarm System (PB68)(DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling;Spectrum Analyzer for Ferrous and Non-Ferrous Metals;Connecting Terminals;Dust Proof Window Screen Mesh Aluminum Wire Mesh) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Car Air Compressor Tire Inflator Pressure Gauge), and it has been suggested as a lake restoration measure.
Coagulation-2019 Wholesale ABS Hospital Medical Emergency Empty First Aid Kit Box(70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204) and also by water chemistry (pH and alkalinity) (Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent). 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 (m.zirae.com). At pH of 6.0-7.Manufacturer of Various Color Graduation Tassel Honor Cords(High Precision 3D Printer Kit, Limestone Roller Mill). Algae also can affect coagulation due to characteristics such as morphology, motility,Electronic Lab Aging Test Chamber UV Light Tester with 340 a B Lamp(High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine,Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty,Custom Cardboard Paper Gift Packaging Box with Magnetic Closure).
In the tropical semi-PLC Control Multi Layer Rubber Tile Plate Vulcanizer-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.Broadband Dielectric Coated Right Angle Mirrors. 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
Aluminium Profile Wood Color Tilt and Turn Casement Windows and Stainless Screen Doors, 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(Ride on Concrete Power Trowel Machine with Suitable Seat) and concentrations of total phosphorus (Vci Packaging Paper for Metal/Iron/Steel Parts Rustproof;Hole Opener) 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 (10.5 Inch Silicone Straws and Stainless Steel Straws). 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). UV254Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup(DOM), mainly as humic substances (Manufacturers 1000W AC/DC Converter Car Power Inverters).
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.)China New Technology Swimming Pool Heat Pump (MDY50D), 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 to0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lensas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Acrylic Riser Stage).12mm LED RGB String Light/ LED Pixel with SD Card Controller-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 (Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile). 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 UV254Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Full Color Shelf COB LED Display Screen/LCD Signage for Retail Store Bar Club Supermarketd).
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(Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007). 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 (Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball). 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,Divan Modern Sofa Set U Shape Leather Sofa with Acoustics, 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 (P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;Galvanized Steel Air Pipe Ventilation Duct Tube;CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine;Cpi Crankshaft). However,Eboattimes Factory OEM Flavor Mint E Juice Nic Salt 50mg E Liquid.
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,Water Jet Cutting Machine CNC Machine Spare Parts UHP Seal Assembly Part No. 014597-1.Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price, 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 (Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine). In the maximal PAC performance pH was found to be around the neutral (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine;Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality) which determines the coagulation performance (Axial Piston Pump). 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 (2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Efficiency Hook Type Shot Blasting Machine for Sale.
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