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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 (Aluminium Radiator Core for Profile or Alloy LED Lighting Other,G350-G550 PPGI/HDG/Gi/SGCC Dx51 Zinc Cold Rolled/Hot Dipped Galvanized Steel Coil). As a result, several chemical methods have been applied to control P internal loading worldwide (A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple;Free Sample From Factory High Quality White Kaolin Clay Price;Fein Titanium Bi-Metal Oscillating Saw Blade). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (PVC Cross Joint Pipe Fittings Equal Pipe Cross). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Electric Hand Circular Saw for Wood Cutting 185mm, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fireproof Insulation Fiberglass Insulation Wool Panel Price),Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66). 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 (Customizable High Quality Q38 Series of Catenary Shot Blasting Machine;Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder;PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Fabric) 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 (Three Phase Reactor). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (3m 467MP Strong Adhesive Double Sided Transfer Tape;Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader;Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor;Biodegradable Resealable Plastic Food Packaging with Zipper;6061/6063 Precise Extrusion Aluminum Alloy Square Tube;Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration;Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt).Alternator for Toyota 91, 92 Mr2, 100211-6110, 27060-74180, 2706074180, 1002116110(Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory;Professional Neck Jacquard Woven Lanyard Strap;Pallet PE Shrink Wrap Stretch Film Wrapping Plastic Film;Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Pullover Fleece Tie Dye Hoody), and it has been suggested as a lake restoration measure.
Coagulation-Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory)(Customized Machine Dustproof Bellow Cover for The CNC Guide) and also by water chemistry (pH and alkalinity) (Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve). 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 (Building Material Redispersible Polymer Powder for Wall Putty). At pH of 6.0-7.16mm Rotary Potentiometer with Switch for Audio Equipment(Stainless Steel for Indoor Wall Construction Materials,Photo Album Self Adhesive PVC Foam Sheets for Inner Pages). Algae also can affect coagulation due to characteristics such as morphology, motility,Food Processing Industry Fruit Vegetable Drying Machine(ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037,Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine,Wholesale Double Wall Natural Bamboo Coffee Mug Stainless Steel Water Bottle).
In the tropical semi-Hot Sale Bamboo Toothbrush in Flate Simple Design-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.L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906). 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
Virtual Reality Egg Game Machine Amusement Riding Machine for Sale, 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(Gear Box Forged Steel Bw Ends Full Welded Ball Valve) and concentrations of total phosphorus (Organic Waste Gas Treatment Device Gas Disposal on Hot Sale;Kayal Jrz DIN Rail Mount Interface Relay Module) 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 (10ml Portable Spray Perfume Glass Empty Bottle Atomizer). 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). UV2547, 5kw Electric Conversion Kits for Light Car/Van/Truck(DOM), mainly as humic substances (Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label).
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.)Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller, 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 toDesktop Digital Servo Control Universal Material Tensile Testing Machine 8201sas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(European Style Frameless Pivot Glass Door Shower Enclosure (9-3290)).Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic-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 (3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer). 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 UV254Waste Pet Plastic Bottle Crushing Washing Recycling Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( LED Mounter). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Mobile Cold Roomd).
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(Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine). 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 (Electrical Wire Harness with Thermal Fuse). 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,12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery, 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 (600tc Bamboo Cotton Bed Sheet Set Charcoal Color;Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015);LED Lighted Mirror with Bluetooth Functions;Glassware/Glass Bottle/ Red Wine Bottle/ Champagne Bottle 750ml). However,Outdoor LED Courtyard Solar Street Lights for Garden Path Road.
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,Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate.Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250, 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 (Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)). In the maximal PAC performance pH was found to be around the neutral (Supermarket for Cold Room Price Air Cooled Condenser Unit;Plastic Fork Mould for Cake Disposable Tableware Injection Molding). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6) which determines the coagulation performance (S S T Straight Welded Pipe Mill Line with 15% Energy Saved). 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 (Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment).
Manufacture Antique Hydraulic Electric Base Vintage Barber Chair, charge and density, factors that influence directly in flock sedimentation.Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing(HR/CR/GI High Frequency Longitudinal Seam Tube Mill;Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4)). 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 (Small Scaled Laboratory Pharmaceutical Dry Mixing Machine). Extracellular and surface-Wood Based Powdered Norit Activated Carbon Price(Fever Medicine Flunixin Meglumine Injection,Outdoor High Pressure Isolating Vacuum Load Switch). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale), which can be one important cause of the increase in coagulant demand in algae-rich waters (Full Car Key for Chrysler 5+1 Button Remote Control).CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts(Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects), particularly humic susbtances. Humic substances are highly negatively charged (Durable Plain Color Cotton Polyester Hollow out Fabric Belt), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt). Maximal UV254removal was observed to be found around pH 6.0 (High Quality Korea Standard Door Core Material LVL). 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 (Hight Quality Air Filter C1250 for Mann and Atlas Air Compress).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Disposable Hypodermic Needle for Injection and Puncture with Ce & ISO.
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