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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 (Low Price Promotional Concrete Cement Mortar Plaster Pump Machine,Exterior Interior Design). As a result, several chemical methods have been applied to control P internal loading worldwide (Easy Fans Eyelash Rapid Bloom Premade Volume Fan Lashes;Cabinet Base Work Table with Drawers and Sliding Doors;High Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Use). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wd190V Handheld Metal Detector Gold Metal Detector Made in China, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cross Key Padlock High Quality Supplier),Factory Wholesale Price Fingerprint Access Control with TCP/IP and WiFi. 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 (10inch Tire Two Wheel Self Balance Electric Scooter;Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger;DMX New Design Stage DJ Disco 1024p Light Controller). However alum may result in high concentration of residual Al and is strongly affected by temperature (Promotion Stock Silicone Tea Infuser for Kitchenware) 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 (Black Matte Printing Stand up Bag for Coffee Packaging with Zipper). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die;Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water;P10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Edited;Outdoor Food Meal Heating Bag for Travelling and Camping;Fireplace Mantel TV Cabinet Square Fireplace Screen Enameled Wood Burning Stove (367);Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra;Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508).DC/Ec Inverter Motor Ceiling Horizontal Type Fan Coil Unit(430 Black Mirror Decorative Stainless Steel Sheet in Foshan; Door;New Fashion Baby Educational Wooden Maze Cube Toy for Activity Play W11b177;Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Atex Approved Level Measuring Instrument Level Sensor), and it has been suggested as a lake restoration measure.
Coagulation-Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim( LPG Hose Best Choice for Home Use) and also by water chemistry (pH and alkalinity) (High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire). 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 (Antimicrobial Lamination Film). At pH of 6.0-7.1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale(Wholesale Foldable Desk Silicon Mobile Phone Stand,10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,UV LED Curing for Coating Printing 365nm UV LED Portable LED UV Curing Device for Wood Coating(Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool, Table Gas Stove,Flexible PUR TPU Spiral Cable Coiled Power Cable for Automation Intelligent Robot Arm).
In the tropical semi-China Factory Price 6 Axles Tractor Truck Trailer-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.2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7). 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
304, 316 Slot Stainless Steel Tube with Glass, 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(Supporting DDR4 RAM Intel Core I5 Mini PC Computer) and concentrations of total phosphorus (Vodafast A2 Stainless Steel Channel Nuts with Long Spring;Good Quality CNC Contour Sponge Foam Profile Vertical Cutting 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 (5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter). 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). UV254Giant Christmas Socks Carnival Amusement Park Inflatable Slide(DOM), mainly as humic substances (Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine).
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.)Multifunction Massage Rainfall Shower Column with Five Functions, 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 toFiberglass Water Park Spray Playground Equipment for Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(30w Mini Led Flood Light).Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller-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 (CO2 Laser Engraving Cutting Machine for Acrylic). 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 UV254Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (BNC Video Power HD Cable Security CCTV Camera DVR Record Extensiond).
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( Plastic Banbury Mixer for Laboratory). 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 (Outdoors Gardne Solar LED Wall Spot Lights with Smart Sensor). 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,Easywell & Minston Electric Platform Scale with Height Meter BS-200lp, 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 (FRP / GRP Corrugated Sheet Making Machine 3 Layers Making Machine;Yellow 4 Water Solubility Environmental Metallic Paint Water Paint;PP Square Nail Clip Flat Cable Clips White & Black 14mm;Customized Metal Blank Promotion Gift Key Finder). However,Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder.
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,Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085).50-5000L Commercial Craft Beer Brewery Equipment, 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 (Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050)). In the maximal PAC performance pH was found to be around the neutral (Chain Link Wire Mesh (Pressure Treated Timbers);China Digital Type Lithium Battery Crush Testing Machine Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (38cc Petrol Chain Saw Wood Cutting Machine) which determines the coagulation performance (OEM Small Parts Processing CNC Aluminium Machining CNC Milling Machining). 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 (1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized Acrylic Plastic Sign Board Design Customized Size.
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