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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 (LED Display Fixed Co Gas Monitor Toxic Gases Analyzing,China Pine LVL Plywood/Lvlwood/Timber Supplier in Linyi). As a result, several chemical methods have been applied to control P internal loading worldwide (Rare Earth Metal Material Cerium Target for Magnetron Sputtering System;Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal;Disposable Rotatable Endoscopic Grasping Net Loop). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Composite Suspension Transmission Insulator String with Electrical Power Fitting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Biodegradable PLA Film for Food /Fruit Packaging, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (corediamtool.com),EU Standard Top Quality Portable Indoor Playground Equipment. 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 (SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker;Aluminum DJ Truss for Exhibition Lighting Truss;Biodegradable PLA Film for Food /Fruit Packaging). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Paver Block Making Machine for Sale) 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 (Factory Car Auto Switch Work Light Bar HID Wire Harness with Relay Fuse). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage;Outdoor Body-Building Sitting Device for Improving Stability of Lower Limbs;Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop; Solar Water Pump for Garden Irrigation (SC Series);m.cnfivestars.com;Smart Label RFID UHF Sticker with Special Offer for Asset Tracking;Painted Black Grade U3 Studless Boat Anchor Chain for Sale).61539 Double Handle 4 Inch South American Style Faucet(2019 Hot Sale Solar Light String Tree Park Decoration Light;New Style Customized Ce Approved Adjustable Inline Skate (SS-179A-BW);Electromagnetic Universal Circuit Breaker Manufacturers Cheap Price;Throttle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruze) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Professional Produce Dmp-430A Vacuum Tray Sealer), and it has been suggested as a lake restoration measure.
Coagulation-3mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration(Digital Universal High Power Ku Band Single LNB Price) and also by water chemistry (pH and alkalinity) (High Quality Centrifugal Industrial Push-Pull Ventilation Husbandary Exhaust Fan). 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 (2 Tons Portable Automatic Lifting Scissor Car Electrical Jack). At pH of 6.0-7.High Temperature Resistant Industrial Cement PPS Air Filter Bag(Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights,Q235 Galvanized Steel Hoop Iron Strap for Packaged Timber House). Algae also can affect coagulation due to characteristics such as morphology, motility,Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver(8PCS*10W RGBW LED Spider Moving Head Beam Stage Light,Best Custom Private Label Glass Pillar Paraffin Votive Birthday Flameless Scented Candle with Jar,Large Volume Military Bag Police Bag Camouflage Bag (SYSG-1811)).
In the tropical semi-Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)-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.HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas. 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
Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture, 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(Paper Making Machine Sand Filter Ceramic Nozzle) and concentrations of total phosphorus (Caprolactam Grade Ammonium Sulphate (21%Min);Pop ups Foil Sheet) 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 (Cheap Plastic Injection Molding/Plastics Mold Making Cheap Price). 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). UV254Kitchen Cleaning Stainless Steel Scourer with Plastic Handle(DOM), mainly as humic substances (12V 24V DC Brushless Centrifugal Circulation Pump).
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.)Digital Pistol Safe Box / 4-Number Digital Safe Box, 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 to3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Stationas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(2p General Relay).Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material-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 (Soyo Energy Aluminum Alloy Solar Ground Mounting System). 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 UV2543 Inch Chinese Brand Full Hydraulic Top Hammer Drill Rig%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.lezpc.comd).
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(Lady Black Mesh Mixed Tank Top Boyshort Two Piece Swimwear). 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 (PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade). 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,Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension, 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 (13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card;100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men;Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO);105mm Square Speaker). However,Stainless Steel Sheet 254smo, Cold Rolled 254smo Steel Sheet.
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,99% High Valued Chemicals Silodosin Intermediates 239463-85-5.Cardboard CO2 100W Tube Tube Laser Cutting Machine, 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 (24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv). In the maximal PAC performance pH was found to be around the neutral (Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg; Filter Pack). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Giant Christmas Socks Carnival Amusement Park Inflatable Slide) which determines the coagulation performance (Color Changing LED Light Big Sofa for Indoor or Outdoor). 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 (Bullet Thermos 350ml Stainless Steel Vacuum Bottle).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet.
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