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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 (Flexible DC12V/24V SMD 2835 Blue Christmas Light LED Strip,180-220grains/Kg New Crop Fresh Chinese Peeled Garlic). As a result, several chemical methods have been applied to control P internal loading worldwide (Pig Breeding Equipment From China Direct Factory;10-100ml Paste Filling Packing Machine for Soy Sauce;Painting Steel Scaffold Planks for Construction). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Outdoor Grey Aluminum Rattan Wicker Woven Beach Lounger Chair). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Inline Water Meter),Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets. 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 (Waterproof Reflective Padded Jacket Safety Working Clothes with Hoodies;Jinan Factory Atc Vacuum Table CNC Router with Cheap Price;Low Cost of 30000kg Single Driver Self-Adjustable Turning-Roll). However alum may result in high concentration of residual Al and is strongly affected by temperature (Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor) 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 (RGBW Moving Head LED Spider Laser Light RGB Diode Laser Projector for Stage). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Small Cable Reel 5m Extension Cord for Home Appliance Humidifier;Factory Supply OEM ODM Tungsten Carbide Seal Ring for Mechanical Seal;Automatic Underground Water Purifying and RO Filter Treatment System;5ton 10m Competitive Price High Quality New Telescopic Forklift;Poultry Automatic Feeder Chain Feeding System for Broiler and Breeder Hens;Automotive Aluminum Engine Parts Low Pressure Casting;Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C).Light Blue Color Glass Drink Bottle for Beer( Aluminum Hurricane Rolling Shutter;Waterproof Carbon Fiber Hard EVA Case for 3D VR;Hardware Parts Assembling Machine;Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Galvanized Steel Spiral Duct for Ventilation Ducting), and it has been suggested as a lake restoration measure.
Coagulation-Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant(Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074)) and also by water chemistry (pH and alkalinity) (Four Wheels Portable Electric Mobility Scooter with Lithium Battery). 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 (China Cnc Flame Cutting Machine). At pH of 6.0-7.Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump(High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine,Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies). Algae also can affect coagulation due to characteristics such as morphology, motility,100W 120W 150W COB LED Street Light Housing(Safety Disposable Shoe Cover for Lab Visitor,Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#),Hifu Woman Skin Care Vaginal Lift for Beauty Machine).
In the tropical semi-15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts-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.Air Bubble Stone as Ozone Diffuser for Air Pump. 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
Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003), 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(Tb10-30kVA Low Frequency Online UPS High Efficiency UPS with Snmp) and concentrations of total phosphorus (Australia Rcm Testing and Certification Service for Power Adapter;4 Axle Oil Diesel Transport Semi Tank Trailer 60000L Fuel Tanker 45tons Oil Tanker 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 (10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment). 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). UV254Purity Veterinary Pharma Grade Albendazole with Competitive Price(DOM), mainly as humic substances (Precision Machining Components for Hydraulic Cylinder Producing).
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.)Trailer Part Coupling, ISO 7241A Quick Release Coupling Qrc 1/2′′npt, 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 toHot Sale Brass Chrome Metal Dish Toilet Bathroom Fittingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bituminous Coal Gasifier).Black PU Auto Car Neck Rest Car Seat Headrest Neck Pillow-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 (Kw-700 Industrial Commerical Driving Type Floor Scrubber Price). 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 UV254Receipt Book/Invoice Book/Business Form Book%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Lifting and Hoisting Industrial Manual Chain Lever Block Vt). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Nightstandd).
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(Quality FTTX Maintenance Tools Effective Fusion Splicers). 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 (Stainless Steel Brass Spring Check Valve (VG12.90081)). 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,Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser 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 (Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture;30cm Round Clear Plastic Pot Plant Trolley;Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home);2019 New Dustbin Cigarette Butt Can Litter Ash Bin Ashtray Stand (SA-106)). However,Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat.
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,Standard Vertical Rotary Automated Smart Tower Car Parking System.Stainless Steel Water Filter Housing RO Systems, 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 (Original Monitor Display Panel for Cat320d Excavator). In the maximal PAC performance pH was found to be around the neutral (China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Sdlg B877f Backhoe Loader Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets) which determines the coagulation performance (High Quality Precision Brass Aluminum Plastic POM Small Mini Turning and Milling CNC Machining Parts). 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 (High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen.
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