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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 (Optical Solar Smoke Detector with Testing Button (ES-T601),Gas Fired Boiler Price). As a result, several chemical methods have been applied to control P internal loading worldwide (Wkj-01/Mechanical Thermostat/ Room Thermostat/HVAC Controls;1.5 Inch High Pressure Petrol/Gasoline Water Pump;15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Waterproof Travel Portable Makeup Bag Wash Gargle Bag). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wicker Willow Flower Garden Gardening Basket, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (www.hncrybcr.com),Automatic Small Round Bottle Water Washing Filling Capping 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 (WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera;Tecjet Cloth Printer Printing Machine 6090 DTG Printer;Home Kitchen Appliance Digital Ozone Generator for Air Water Purifier). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hastelloy C276 Uns N10276 2.4819 Plate Bar Tube Nickel Alloy with China Supplier) 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 (Promotion Cheap Price High Quality Food Grade Disposable Plastic Food Storage Container). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel;Automotive Electropainting;Aluminium Radiator Core for Profile or Alloy LED Lighting Other;A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple;Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass;Free Sample From Factory High Quality White Kaolin Clay Price;Fein Titanium Bi-Metal Oscillating Saw Blade).Tungsten Carbide Cold Heading Dies for Screws and Nuts(PVC Cross Joint Pipe Fittings Equal Pipe Cross;Customizable High Quality Q38 Series of Catenary Shot Blasting Machine;High Grade Nano Particel Size Cerium Oxide CEO2 Powder;Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector), and it has been suggested as a lake restoration measure.
Coagulation-201 Stainless Steel Coil /Stainless Steel Sheet /Stainless Steel Plate( Fabric) and also by water chemistry (pH and alkalinity) (3m 467MP Strong Adhesive Double Sided Transfer Tape). 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 (HBsAb). At pH of 6.0-7.Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass(Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader,Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor). Algae also can affect coagulation due to characteristics such as morphology, motility,Deep Drawing 300tons Sheet Metal Stamping Hydraulic Press Machine 100tons(Biodegradable Resealable Plastic Food Packaging with Zipper,Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration,Flexible Pcb).
In the tropical semi-Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly-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.Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line. 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
18inch Industrial 3 in 1 Fan-Stand Table Fan, Wall Fan 3 in 1-Competitive Price, 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(Professional Neck Jacquard Woven Lanyard Strap) and concentrations of total phosphorus (Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck;Gear Ring) 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 (Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve). 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). UV254off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit(DOM), mainly as humic substances (Stainless Steel for Indoor Wall Construction Materials).
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.)Durable Rectangular FRP Pultruded Grating for Glassfiber Platform, 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 toSingle Prong Metal Chrome Pegboard Bracket Merchandising Display Hookas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Half Body Portable Far Infrared Sauna with Foldable Tent).Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed-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 (Organic Waste Gas Treatment Device Gas Disposal on Hot Sale). 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 UV25455 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (350W 17r Outdoor Moving Head Lights DJ Move Chinese Moving Heads Moving Spot Lightsd).
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(10ml Portable Spray Perfume Glass Empty Bottle Atomizer). 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 (Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label). 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,New 14 Inch Diamond Saw Blade for Granite Cutting, 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 (2019 New Bio Vacuum Cavitation RF 6 in 1 Fat Freezing Body Slimming Salon SPA Machine;Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s;Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw;Precision Sand Casting). However,Fancy Corn Starch Disposable Round Plate with Stripe for Party.
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,Manhole Cover Stainless Manway Tank Hatch Cover.Biodegradable Resealable Plastic Food Packaging with Zipper, 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 (New Design Expanded EPE Foaming Extrusion Machine for Electric Packing). In the maximal PAC performance pH was found to be around the neutral (3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer; LED Mounter). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Cheap Price Creative Style Design of Men′s Leather Slippers) which determines the coagulation performance (French Fries Fryer). 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 (Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer.
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