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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 (Custom Aluminum Steel CNC Machining Mechanical Turning Parts,Led Message Fan With Mirror). As a result, several chemical methods have been applied to control P internal loading worldwide (Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands;2 Ton Brand New Small Cheap Backhoe Loader for Sale;Galvanized Wire Fence Building Barbed Wire Fence Pictures). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fiber Laser Marking Machinery for Engraving Ribbon Metal Stainless Steel). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Chinese Product Mini 32A 4p Household AC Contactor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (160lm/W Radar Detector 1500mm T8 LED Tube Light),Natural Wave Brazilian Virgin Human Hair Extension. 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 (Factory Manufacturer CNC Dual Use Combined Metal Sheet Plate & Tube Pipe Fiber Laser Cutter;3.0V 4mm Diameter Coreless Mini Strong Vibration Motor with Bracket;Combustibility Analyzer Flame Testing Equipment for Building Material ISO 11925). However alum may result in high concentration of residual Al and is strongly affected by temperature (35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck) 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 (Smart Kitchen Tool Food Grade Heat Resistant Silicone Spoon Mat). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (China Factory Supply 25mm Blackout Pleated Honeycomb Blinds;China Manufacturers Round Welded Stainless Seamless Steel Pipes 316;Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring;4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring;Manganese Steel Sandvik Cj412 Cj612 Cj615 Jaw Crusher Spare Parts Tooth / Jaw Plate;Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts;All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J)).Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch(High Speed Metal Pipe Automatic ERW Welded Pipe Machine;DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil;Child Style Swing Pod Outdoors;Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Pressure Zirconia Ceramic Piston Rod Pump Ceramic), and it has been suggested as a lake restoration measure.
Coagulation-Diesel Fuel Leak off Pipe for Mercedes-Benz( Skateboard Shoes) and also by water chemistry (pH and alkalinity) (Kids Electric Car with 12V Battery Remote Control). 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 (1000 Style Chorme Plating PVD Vacuum Coating Machine for Stainless Steel Ceramic Glass). At pH of 6.0-7.Portable Medical Ozone Therapy Unit Zamt-80 on Sale(Wholesale Wehappy Silicone Baby Training Toothbrush Set with Blister Card Package,Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308)). Algae also can affect coagulation due to characteristics such as morphology, motility,43L Big Volume Insulated Backpack Delivery Food/Pizza Bag(Auto Parts for Plastic Products Injection Mould Mold Tooling,904L Stainless Steel Press Sheet with Hl Surface Finish,Gas Spare Parts).
In the tropical semi-1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die-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.Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid. 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
Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair, 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(Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards) and concentrations of total phosphorus (Precision Large 3 Axis Bench Metal Milling Machine Lm1450c;Antioxidants In Plastics) 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 (Continuous Inkjet Printer for Plastic Pipe Printing (EC-JET1000)). 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). UV254Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls(DOM), mainly as humic substances (Standard Air Small Sandblaster for Construction Machinery Cleaning).
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.)Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector, 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 toTransparent Single Crystal Alumina Sapphire Jewel Bearing and Componentsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Qt6-15 Automatic Concrete Hollow Brick Making Machine Curbstone Block Making Machine for Sale).40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine-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 (4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for 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 UV254Hot Sale High Density Hotel Cashmere Wool Polyester Blanket%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM/ODM Custom Precision Copper/Aluminum /Bronze /Carbon Steel/Stainless CNC Machining Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Chew Rope Dog Toyd).
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(New Design Contact Infrared Baby Ear Thermometer Jl0158). 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 (Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System). 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,Home Furniture Metal Chair Grey Velvet Dining Chair, 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 (6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper;Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine;20K Ohhm 1% Electrical Ntc Thermistor Resistance;Flash Led Light Pcb). However,168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale.
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,OEM High Efficiency Polycrystalline 260W Solar Panel.Basketball Rebounded Practice Machine for Professional Trainer (S6839), 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 (OEM Customized Aluminum Die Casting Automotive Parts Die Casting Die). In the maximal PAC performance pH was found to be around the neutral (Hex B19 B22 Integral Drill Rod Steel /Shank Drill Road/Tapered Drill Rods; Truck Parts). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (16oz Pet Plastic Food Jar with Embossed Metal Lid (PPC-PJ-1701)) which determines the coagulation performance (Electrical DC PMDC Motor for Industrial Deduster). 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 (Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding).
DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil, charge and density, factors that influence directly in flock sedimentation.Customized Sand Casting Brake Wheel Hub for Trailer and Truck(Custom Design Stainless Steel Sheet Metal Fabrication Box Cover;Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula). 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 (Cartoon Design Decorative PVC Sheet for Wall Panel Moulding). Extracellular and surface-Solid Surface Stone Table Top Restaurant Black Round Dining Tables(etonsmtauto.com, Skin Care). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (3003 3004 3005 Aluminium Circles for Foil Pans with Lids), which can be one important cause of the increase in coagulant demand in algae-rich waters (All Round Inflatable Stand up Paddle Boards for Surfing).Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch(Fiberglass FRP Sandwich Panel for Insulation Truck Body Construction), particularly humic susbtances. Humic substances are highly negatively charged (Plush U Shape Pillow Stuffing Microbead Soft Neck Pillow EPS Travel Pillow), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery). Maximal UV254removal was observed to be found around pH 6.0 (Carbon Stick Welding Electrodes E6013&E7018 Stone Bridge Brand). 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 (Compact Laminate Kids Urinal Screen with Good Price).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Curve Spear Tunnel Bolt for Concrete Ring.
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