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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 (Small Cable Reel 5m Extension Cord for Home Appliance Humidifier,Lab Rubber 2 Mixing Mill). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Supply OEM ODM Tungsten Carbide Seal Ring for Mechanical Seal;Automatic Underground Water Purifying and RO Filter Treatment System;5ton 10m Competitive Price High Quality New Telescopic Forklift). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Automotive Aluminum Engine Parts Low Pressure Casting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Galvanized Perforated Metal Sheets, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Drinker For Chicken),Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997). 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 (Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C; Aluminum Hurricane Rolling Shutter;Waterproof Carbon Fiber Hard EVA Case for 3D VR). However alum may result in high concentration of residual Al and is strongly affected by temperature (Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine)) 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 (Cow Leather Safety Gloves). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Galvanized Steel Spiral Duct for Ventilation Ducting;Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074);Four Wheels Portable Electric Mobility Scooter with Lithium Battery;High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine;High Quality Stainless Steel Flash Drying Machine From China;Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies;Safety Disposable Shoe Cover for Lab Visitor).Automotive Electropainting, Electrophoretic Coating, Electrodeposition Machine for Sale(Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#);High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754);Professional Manufacturer for Aluminum Three-Track Sliding Window and Sliding Door;New Items Personalized Teething Toy Baby Pacifier with Panda Shape) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Tb10-30kVA Low Frequency Online UPS High Efficiency UPS with Snmp), and it has been suggested as a lake restoration measure.
Coagulation-Dental Emax Empress Crown From China Dental Lab(Australia Rcm Testing and Certification Service for Power Adapter) and also by water chemistry (pH and alkalinity) (1/4 Inch 300 Psi Rubber Hose for Compressor Air). 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 (PVC Powder Conical Twin- Screw Pelletizer /PE Recycling Plastic Granulator). At pH of 6.0-7.Aluminum DJ Truss for Exhibition Lighting Truss(Receipt Book/Invoice Book/Business Form Book,10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables(Precision Machining Components for Hydraulic Cylinder Producing,Professional Salon Use Plastic Hair Coloring Comb,m.mphotoluminescent.com).
In the tropical semi-Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials-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.80% Cotton 20% Polyester Colorblock Men′s Fleece Pull Over Raglan Hooded Sweatshirt. 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
Androst 3 5 Dien 7 17 Dione Raw Steroid Powders Fat Burning Prohormones CAS 1420-49-1, 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(Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting) and concentrations of total phosphorus (Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar;200mm Ductile Iron Pipes) 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 (Lifting and Hoisting Industrial Manual Chain Lever Block Vt). 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). UV254Mini Horizontal Axis 100W Wind Generator Turbine(DOM), mainly as humic substances (Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set).
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.)programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card, 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 toUSA American and Canada 110V UL NEMA 5-15 Power Extension Cordas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Casting).Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable-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 (Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home)). 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 UV254Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Original Monitor Display Panel for Cat320d Excavator). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (CO2 Acrylic Materials Products Laser Marking Machined).
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(Sdlg B877f Backhoe Loader Price). 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 (Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets). 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,Thin Wall 7049 7050 Aluminum Tube with PVC Package, 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 (High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals;Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine;Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525;Mds Series High Temperature Heat Pump Factory (MDS30D)). However,Impa651710 Marine Wholesale Seawater Thermometer.
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,Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787).Breathable Pet Dog Shoes with Reflective Magic Tape Straps, 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 (Micro Water Tank Level Transducer for Wall Hung Gas Boiler). In the maximal PAC performance pH was found to be around the neutral (High Temperature Alternative Stainless Steel Band in Different Package;Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner) which determines the coagulation performance (Private Labeling Teeth Whitening Strips Customized Teeth Whitening Gel Strips). 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 (New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges).
Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker, charge and density, factors that influence directly in flock sedimentation.Best Price 1325 Woodworking CNC Router Machine Equipment(Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Hf Vacuum Dryer Machine with Advanced High Frequency Technology). 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 (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine). Extracellular and surface-8FT Wood Log Debarker Machine for Plywood Machinery(Hand Sanitizer Case,700mm RP HP UHP High Quality Graphite Electrode). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch), which can be one important cause of the increase in coagulant demand in algae-rich waters (Furniture Laminate Sheet/HPL Panel/Building Material).OEM Hardware Factory Custom Fabrication CNC Aluminum Signet(7), particularly humic susbtances. Humic substances are highly negatively charged (Store Display Rack), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale). Maximal UV254removal was observed to be found around pH 6.0 (Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant). 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 (Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.on-off Automotive Switches Automotive Rocker Switch 16A Rocker Switch.
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