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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 (Women Footwear Ballerina Casual Shoes With High Quality,A Cement Truck). As a result, several chemical methods have been applied to control P internal loading worldwide (250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps;3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable;Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Enginerring Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (PVC Sliding Window),Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence. 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 (Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant;Supermarket Island Freezer;Carbonizing Kiln Furnace for Making Coconut Shell Charcoal). However alum may result in high concentration of residual Al and is strongly affected by temperature (Construction Equipment 1.5 Cube Materials Portable Concrete Mixer) 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 (Collecting Bucket Street Sweeper Mini Telescopic Wheel Loader of 10km/H). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;High Speed 6 Color PP Woven Bag Printing Machine;Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors;600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;Modular 150lm/W Flat 50W 5FT Cool Warm Linkable PRO LED Linear Trunking System Light;1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable;Disposable TPE Gloves).2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink(250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top;1.2V 3600mAh 4/3A size rechargeable NiMH Battery;High Quality Customized HDMI to Displayport Cable;12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Energy Ejector Venturi Gas Scrubber System), and it has been suggested as a lake restoration measure.
Coagulation-20qt Portable Small Rotomolded Insulated Medical Cooler Box(Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet) and also by water chemistry (pH and alkalinity) (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). 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 (www.alsichina.com). At pH of 6.0-7.Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale(Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile,Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC). Algae also can affect coagulation due to characteristics such as morphology, motility,Color Coated Prepainted Aluminum Sheet/Coil(Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry,RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats,Blow Mould For Ip Ducts For Car Air Conditioner).
In the tropical semi-Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)-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.Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric. 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
430 Hot Rolled Stainless Steel Coil No. 1 Finish, 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(Ideabond Aluminum Composite Panel Brushed Series) and concentrations of total phosphorus (Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation;Co2 Cartridges Argon Gas Capsule) 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 (Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking Machine). 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). UV254Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale(DOM), mainly as humic substances (Aluminum Recovery Fill Tank for C-4 84-96 Chevrolet Corvette).
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.)Customized Embossing Logo Soft Flexible PVC Bar Mat, 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 toReplacement LCD Digitizer for Apple iPhone 6plusas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Products).Concrete Stone Cutting Diamond Chain Saw on Sale-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 (Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet). 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 UV254Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Top Quality Precision Floor Industrial 2 Ton Weighing Scale). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (General Household Hardware Hand Tools Setd).
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(Luxury Black Color Shower Door and Shower Enclosure (MB-226)). 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 (Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery). 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,RO Water Treatment Plant Water Purifying System Water Filter 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 (2.5m Commercial Combined Island Display Showcase Freezer for Supermarket;Solid Surface Grade Grinding Alumina Tyihydrate;LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture;New Biological Microscope LED 100X-1200X Home School Educational Toy Gift Kids Microscope). However,High and Low Temperature Humidity Chamber for Cycling Control.
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,Install High Density Hardie Ceiling Tile Fiber Cement Board.Aerospace Industry Cutter Systems/ Equipment Cutting Plotter CNC 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 (45 Degree Copper Pipe Joint in Air Conditioner). In the maximal PAC performance pH was found to be around the neutral (Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid;High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hydra Diamond Microdermabrasion Peel Facial Machines) which determines the coagulation performance (Sauna Electronic RFID Card Cabinet Locker Lock). 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 (Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Factory Polyester Solid Color Single /Double Faced Satin Ribbonfor Wedding Chirstmas.
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