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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 (High Density Wood Grain Fiber Cement Board,Bearing 6206 2z C3). As a result, several chemical methods have been applied to control P internal loading worldwide (1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar;Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread;Cow Horse Trailer Ramp Stall Stable Rubber Mat). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hydrochloric Acid (HCl) ). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Single-Port Magnetic Modular Jacks with LED),Rotary Dryer for Sawdust, Drum Sand Rotary Dryer. 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 (Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover;7 Liters Vertical Type Commercial Butchery Manual Sausage Filler;Mica Fiberglass Braided High Temperature Electric Power Cable). However alum may result in high concentration of residual Al and is strongly affected by temperature (Manufutuer Promotes Skin Regeneration Repair Anti Aging Smoothing Fine Lines Facial Mask) 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 (China Colour Changing Spotlights). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Portable Animal High Frequency X Radiography Machine (HP-HFX600V);Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold;Cement Bag Manufacturer Kraft Paper Valve Bag for Cement;Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling;Healthy Hormone Polypeptide Dsip (2mg/vial) Delta Sleep-Inducing Peptide;Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag;PC260 3.0-24V 24*27mm 3W DC Motor for Electric Garden Tool).2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC)(LED Dancing Wing Props Halloween Christmas Party Supplies;Glass Shower Door Frame Waterproof Seal PVC Seal;Manufacturer Non-Ferric Aluminium Sulphate Al2 (SO4) 3 Flake/Granular/Powder;2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel), and it has been suggested as a lake restoration measure.
Coagulation-Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market(12mm Multiwall Green Perforated Hollow Polycarbonate Sheet) and also by water chemistry (pH and alkalinity) (Best Quality Tianeptine Acid / Tianeptine CAS 66981-73-5). 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 (Ride on Car Christmas Plush Decoration Gift Toy). At pH of 6.0-7.Durable Board of Roadway No Parking Sign Board PE Traffic Cone(Chiller Price Water Cooling System Screw Air Cooled,1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD). Algae also can affect coagulation due to characteristics such as morphology, motility,New Design Brass IP68 LED Underwater Fountain Light( NdFeB Magnet for Motor (N38H),15kg Big Payload Unmanned Aerial Vehicle (uav) with Various Camera Payload Optional,Black Acoustic Ceiling Tiles).
In the tropical semi-Intelligent Roll Printing Machine for PP Woven Sack Printer-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.Outer Side Mirror Left and Right Rearview Mirror for Skoda. 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
Outdoor Food Truck Mobile Food Car 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(Customized Ring Die for 560/508/420/350 Pellet Machine) and concentrations of total phosphorus (New Slimming Product Grapefruit Weight Loss Capsule;Booster Solar Pump Suppliers for Sale) 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 (Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator). 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). UV254C6251 lathe machine specification gap bed lathe machinery universal lathe machine(DOM), mainly as humic substances (Metal Pot Scourer Used of Stainless Steel and Galvanized).
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.)High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet), 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 toBest Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot DIP Galvanized Steel U Channel Grating200X90mm).2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster-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 (Traffic Safety Water Filled Plastic Road Barriers). 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 UV25410.5 Inch Silicone Straws and Stainless Steel Straws, No-BPA Reusable Drinking Straws%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (HPMC for White Cement Admixtures Putty Powder Additives). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (CNC Milling Aluminum Mold Die Casting Machine Partsd).
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(High Energy Wet Pulverizer and Wet Powder Mill). 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 (Aerospace Industry Cutter Systems/ Equipment Cutting Plotter CNC Cutting Machine). 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,High Performance Bright Annealing Stainless Steel Welding Tube Mill 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 (Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean;OEM Custom 2pieces Car Rims 17 18 19 20inch Forged Car Alloy Wheels;Pet Strapping Belt Making Machines/Pet Packing Straps Extrusion Machine;Telescopic Rod). However,Woma Acrylic Shower Panel Cubicle Room for Old People (Y698).
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,Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting.MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration, 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 (Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press). In the maximal PAC performance pH was found to be around the neutral (BRT Gasoline Log Splitter 22 Ton Firewood Processor;Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid) which determines the coagulation performance (Plastic Welding Machine). 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 (Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom).
Sf606 Serve Motor Automatic Wood Cut off Saw Machine, charge and density, factors that influence directly in flock sedimentation.Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer(Cotton/Polyester/Spandex Interlock for Clothing;Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine). 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 (Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform). Extracellular and surface-Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)(Heating Furnace Stove Fireplace Brass Connector Water Pipe Fitting,Cheap CNC Leather Oscillating Knife Cutting Machine Milling Head Knife Head Cutter). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate), which can be one important cause of the increase in coagulant demand in algae-rich waters (Z21 Type High Precision Flexible Locking Coupling Assembly Device).Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches(Certified 100% Natural & Pure Organic Basil Herbs Oil), particularly humic susbtances. Humic substances are highly negatively charged (Modern Wooden Sideboards), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Class125 Double Disc Wafer Swing Check Valve). Maximal UV254removal was observed to be found around pH 6.0 (Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways). 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 (Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil.
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