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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 (Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine,7W Sand White Single LED Grille Light Venture Lamp). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Price Capstan Hydraulic Winch 5 Ton;Washroom Water Tap of Hot and Cold Water Mixer;Low Insertion Loss St Upc Singlemode Simplex Fiber Optic Adapter). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (China Most Professional Factory 316L Stainless Steel Round Seamless Decorative Pipe Tube). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Strip Metal Stainless Aluminum Mosaic),Commercial Promotion White Inflatable Party Tent for Exhibition. 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 (Living Room Furniture TV Stand Electric Fireplace with No Heating;High Quality 11oz Bone China Color Change Mugs Sublimation Coating Mugs (Matte);Smart Electronic RoHS Weighing Scale PCB Manufacturer with Fast Delivery). However alum may result in high concentration of residual Al and is strongly affected by temperature (Zinc-Plated Carbon Steel Tiger Clamp Spiral Double Bolts Clamp) 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 (1200W Electric Portable High-Quality Jet High Pressure Washer/Cleaner). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Best Electric Roll on Paraffin Wax Heater for Sale;Industrial Series Mbar Low Pressure Gauge with Phenolic Case; Pipe Flanges Schedule 40;Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu;Jewelry Blank Bangles;IP65 60W Solar LED Street Light with WiFi Camera;Aluminium Sand Casting Foundry Sand Casting Products with Sand Blasting Finish).Camping Gas Stove, Outdoor Stove, Table Gas Stove(Factory Wholesale Car Accessories Universal 4X4 Roll Bar;High-Temperature Refractory Silicon Carbide Roller Used in Kiln Furniture;Stainless Steel Mesh Strap Men Watch Quartz Movement Alloy Case;Hot Selling Screw Conveyor/Screw Conveying System with Low Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ss Stainless Steel 90 Degree Street Elbow Threaded Pipe Fittings), and it has been suggested as a lake restoration measure.
Coagulation-Toroidal Power Transformer for Household Audio(Electric Ride on Kids Car Battery Operated Toys Car) and also by water chemistry (pH and alkalinity) (P6.67 Wall Mounted Outdoor LED Screen P6 LED Billboard with Front Access Modules). 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 (Giantmay Professional Beverage Display Energy Drink Stand Shelf Metal Basket). At pH of 6.0-7.Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift(Automatic Vacuum Packing Premade Tray Filling&Sealing Machine,Miniature Linear Motion Guide Mgn5/Mgn7/Mgn9mgn12/Mgn15 Square Linear Block). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print( Power Unit Pack 3200 Psi Fit for Lift up/Down,Factory Price Zinc Sulphate 33% Granular Tech Grade,Best Dry Cabinet Brand).
In the tropical semi-Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale-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.OEM 15t Conveyor Cast Iron Simplex Duplex Triplex Chain Sprocket Gear. 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
Counter Top Chips Worker Infrared Chips Warmer, 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(Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts) and concentrations of total phosphorus (Online Shop China White Sticky Painter Felt Roll;Pet Yarn Making Machine) 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 (Handle Adjustable Magic High Quality Microfiber Magnet Mop for Home Cleaning 1045). 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). UV254100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll(DOM), mainly as humic substances (Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder).
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.)Type F High-Rise Clip Drive/Worm Hose Clamp, 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 toIndoor FTTH 96 Cores Distribution Loose Tube LSZH Fiber Optic Cableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ceramic Tile Bathroom Floor).Ferrite Magnet Used in Motor as Magnetic Strip-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 (Manufacturer New Design Reusable Clear Lalique Glass Perfume Packaging Bottle). 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 UV254Large Diameter ASTM A213 TP304L Seamless Stainless Steel Pipe%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (BOPP PE PVC PP Slitting and Rewinder Machineryd).
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(380W New Beam Moving Head Night Club Disco Lighting for DMX Controller). 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 (Large Diameter ASTM A213 TP304L Seamless Stainless Steel Pipe). 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,Hot Sale and Good Quality Playground Artificial Lawn for Soccer, 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 (Jmc Vacuum Road Dust Truck Mounted Sweeper Car;for Steel Arc Furnace Use The Quality Should Be Good Certified Grades;Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade;White Melamine Paper Faced Blockboard /18mm Poplar Core Blockboard). However,Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding.
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,Plastic RGB LED Round Dining Table for Wedding Lights Decorations.Low Cost of 30000kg Single Driver Self-Adjustable Turning-Roll, 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 ( Aluminum Parts). In the maximal PAC performance pH was found to be around the neutral (Thermal Insulation Rubber Foam Pipe for Air Conditioning;Food Grade Composite Packaging Standup Plastic Pouches Bag with Zipper). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys) which determines the coagulation performance (Kunststof Water PE Pipe Buis Voor Water / Gas Transport). 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 (Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Transport Dumper Truck 30 Ton Payload Zf Transmission 420HP.
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