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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 (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type),304 Stainless Steel Strapping Band). As a result, several chemical methods have been applied to control P internal loading worldwide (Women Footwear Ballerina Casual Shoes With High Quality;250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps;3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Tablet Machine Manual),Thermoplastic TPE Granules Making Machine for Grass Filling. 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 ( Enginerring Machine;Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant;Supermarket Island Freezer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal) 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 (Carbon Steel Water Pipe Flange 200mm Metal GRP FRP Tank Flange). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Construction Equipment 1.5 Cube Materials Portable Concrete Mixer;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;Engine Gta42 Turbocharger 612630110258 for Steyr Wd615;600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable).7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck(Disposable TPE Gloves;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top;4;1.2V 3600mAh 4/3A size rechargeable NiMH Battery) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS), and it has been suggested as a lake restoration measure.
Coagulation-Hf Vacuum Dryer Machine with Advanced High Frequency Technology(High Energy Ejector Venturi Gas Scrubber System) and also by water chemistry (pH and alkalinity) (Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet). 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 (Spindle Motor 2.2kw). At pH of 6.0-7.Forged Custom Exterior French Door Wrought Iron Double Entry Doors(Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising,Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile). Algae also can affect coagulation due to characteristics such as morphology, motility,New Model Cheap Unique Fashion Jewelry 925 Sterling Silver CZ Stud Earrings for Girls(Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC,Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry,MEK Ffp1 Ffp2 Ffp3 Folded Dust Mask for Personal Use).
In the tropical semi-Joylive Car Lift Goods Elevator Used Home-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.Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light. 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
Poultry Farm Chicken House Breeding Farm Machinery H Type Layer Cage, 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(Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture) and concentrations of total phosphorus (Ideabond Aluminum Composite Panel Brushed Series;Cabinet Industrial Food Dryer) 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 (3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench). 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). UV254Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6(DOM), mainly as humic substances (Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking 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.)Diesel Engine Mobile Rotary Screw Scroll High Pressure Air Compressor, 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 toFactory Best Price Portable and Oprional Steam Generator Saunaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Home Flake Ice Machine).Juki Flexible Mounter LED Placement Machine, LED Mounter-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 (Bearing Accessories Bearing Ball Bearing Rollers). 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 UV254Factory Directly Ss 304 Stainless Steel Toilet Cubicle Fitting Indicator Latches%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Baby Diaper Production Equipmentd).
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 Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration). 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 (Luxury Black Color Shower Door and Shower Enclosure (MB-226)). 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,PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material, 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 (Solid Carbide Straight Slot Reamer with Inner Cooling Hole;2.5m Commercial Combined Island Display Showcase Freezer for Supermarket;Solid Surface Grade Grinding Alumina Tyihydrate;Model Kp 100W 120W 150lm/W 6FT LED Linear High Bay). However,Non-Toxic RTV Silicone Sealant of Full Automatic Machine.
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,Plastic Logistics Daily Use Plastic Injection Crate Mould.6 Head Garment Computerized Embroidery Machine Industrial Use for Sale, 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 (LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture). In the maximal PAC performance pH was found to be around the neutral (45 Degree Copper Pipe Joint in Air Conditioner;Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader) which determines the coagulation performance (Best Price Led Helium Ballons). 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 (Hydra Diamond Microdermabrasion Peel Facial Machines).
20K Ohhm 1% Electrical Ntc Thermistor Resistance, charge and density, factors that influence directly in flock sedimentation.Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone(Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence;New Arrivel Grand Sale Wholesale Soft Fishing Lure). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group). Extracellular and surface-Alumina Ceramic Shafts Al2O3 Ceramic Plungers(Black Factory Made Lotion Cream Pump for Cosmetic Packaging,Manufacturer Woven Patches and Customized Woven Badge). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Provide Low-Volume Production Injection Moulding), which can be one important cause of the increase in coagulant demand in algae-rich waters (Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank).Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets(LG Mj1 3500mAh 3.7V Rechargeable 18650 Lithium Battery for Power Bank), particularly humic susbtances. Humic substances are highly negatively charged (www.qihebiotech.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Model C823 Intelligent Quick Charger Suit for iPhone Cable). Maximal UV254removal was observed to be found around pH 6.0 (18000CMH Portable Commercial Industrial Evaporative Mobile Water Air Cooler). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Lab Paddle Blender/Stomacher Blender /Sterile Homogenizer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Large Industrial Ceiling Fan with External Rotor Motor Drive.
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