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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 (3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer,Sparkly Sequin Fabric). As a result, several chemical methods have been applied to control P internal loading worldwide ( LED Mounter;Cheap Price Creative Style Design of Men′s Leather Slippers;Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Electrical Wire Harness with Thermal Fuse). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Individually Wrapped Paper Straws Compostable Paper Drinking Straws, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (www.hongraygloves.com),Flanges Male Female Fittings Assembled with Flexible Metal Hose. 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 (Bathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drain;Rainbow Rafting Fiberglass Aqua Water Park Slide;600tc Bamboo Cotton Bed Sheet Set Charcoal Color). However alum may result in high concentration of residual Al and is strongly affected by temperature (Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)) 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 (Work Light With Sos). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (LED Lighted Mirror with Bluetooth Functions;Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X);Supermarket for Cold Room Price Air Cooled Condenser Unit;Plastic Fork Mould for Cake Disposable Tableware Injection Molding;Welding Fixture;Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6;Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment).Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller(HR/CR/GI High Frequency Longitudinal Seam Tube Mill;Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4);Digital LED Desktop Digital Table Mirror Alarm Clock Thermometer;Small Scaled Laboratory Pharmaceutical Dry Mixing Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Outdoor High Pressure Isolating Vacuum Load Switch), and it has been suggested as a lake restoration measure.
Coagulation-Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment(Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale) and also by water chemistry (pH and alkalinity) (Full Car Key for Chrysler 5+1 Button 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 (Nano Oxygen Generator). At pH of 6.0-7.Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm(Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects,ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic 2 Color Screen Printing Machine for Bottle Lids with UV Curing System(High Quality Korea Standard Door Core Material LVL,Hight Quality Air Filter C1250 for Mann and Atlas Air Compress,XCMG Lifting Construction Machinery 25 Tons Mobile Truck Crane Qy25K-II).
In the tropical semi-Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire-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.Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine. 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
Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price, 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(Self-Adhesive Non-Slip Sticky White Felt for Easy Painter) and concentrations of total phosphorus ( Round Jaws Lock Wrench Wr Type;SUS 202 304 316 Customization Processing Block Stick CNC Machining) 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 (Large 25X100m Exhibition 2500 Seat Tent for Trade Show). 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). UV254Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu(DOM), mainly as humic substances (Custom Made Round Shape Cardboard Dry Fruit Gift Paper Box).
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.)Large Size Double Flange Rubber Lined Butterfly Valve with Worm Gear Operated, 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 toProgrammable Ozone Aging Test Equipment for Rubber Cable Resistanceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cnc Milling Machine).Perfect Protection for Guideways of Stainless Steel Telescopic Way-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 (Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt). 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 UV254High Precision Machinery Plastic Parts with Injection Mold%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (WEDGE WIREd).
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(Multi Function Power Tool Oscillating Saw Blades (1-3/8 34mm Japanese Tooth) Fit Makita). 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 (Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining). 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,Kynko Li-ion Cordless Drill with 18V Battery (KD30), 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 (4X Laser Iridium Spark Plugs Pzfr6r 5758 for Audi A1 A3 VW Passat EOS Skoda Seat;1 Holder Mobile Electric Stainless Steel Plate Warmer Cart;Custom Own Shoes Bag Garment Brand Logo PVC Rubber Label/PVC Patch/Accessories for Cloth;60kw 120V/240V Two Voltage Output Split Phase Pure Sine Wave off Grid Hybrid Inverter). However,304 Stainless Steel Pipe Manufacture in China.
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,3D Finish Soundproof Movable Partition Wall for Meeting Room.1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine 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 (Gear Operated Cast Iron Wafer Type Butterfly Valve). In the maximal PAC performance pH was found to be around the neutral (Street Lighting 50W 100W 150W 200W LED Street Lamp Source Outdoor LED Street Light;Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Clear Acrylic Chinese Tea Table (BTR-Q1012)) which determines the coagulation performance (Kxf0dkcaa00 745X8.5X0.65mm Panasonic Flat Conveyor Belt). 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 (Stainless Steel Electric Heating Mixing Kettle for Food Industry).
Nr, EPDM Rubber Buffer for Auto, Machinery, Air Conditioner, charge and density, factors that influence directly in flock sedimentation.High Quality 11oz Bone China Color Change Mugs Sublimation Coating Mugs (Matte)(High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line;High Quality C5/C3 Grinding Ball Screw From Taiwan). 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 (High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing). Extracellular and surface-Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador(Factory Sale Hotel Bank Safes for Electrical Safe Box Guest Safe Deposit Box,Manufacturer of Various Color Graduation Tassel Honor Cords). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router), which can be one important cause of the increase in coagulant demand in algae-rich waters (Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W).Guard Rail Roll Forming Machine 2.0-4.0mm Thickness(China Label Screen Printing Machine Suppliers), particularly humic susbtances. Humic substances are highly negatively charged (Pipe mould), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( Water). Maximal UV254removal was observed to be found around pH 6.0 (Ring Die Sawdust Wood Pellet Making Machine Line). 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 (Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Flexible Semiauto Cosmetics Bottles Adhersive Labels Sticker.
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