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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 (Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift,Bluetooth Selfie Stick Tripod). As a result, several chemical methods have been applied to control P internal loading worldwide (125kHz RFID Tag Tk4100 IC Epoxy Card with Smart Card;5um Metallized Polypropylene Film Single Sided Capacitor Film;Ladies Fashion PU Leather Mini Backpack for Girles). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Roller Frame). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (3 Inch 4 Inch 5 Inch 6 Inch Galvanized U Bolt Clamp),1/2 Inch Brass Stem Handwheel Gate Globe Valve. 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 (Shoe Mold Metal Engraving Milling CNC Mould Making Machine;Customized Bar and Plate-Fin Excavator Oil Radiator /Water Radiator;High Efficiency Complete Italy Pasta Production Line). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Multi Function Side Drilling 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 (Uhf Tag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Yh1650 15′′ Retractable Cable Wire Trigger Key Lock Gun Lock;Hot Selling Mini Am RF Security Hard EAS Pencil Tag for Clothing Store;7.00-20 Tube Rim TBR Truck Steel Wheel with TS16949/ISO9001: 2000;CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist;Factory Directly Sell Lvt PVC Vinyl Flooring Tiles / Planks;Hot Sale Alkaline Water Purifier Water Machine Alkaline Water Ionizer or Alkaline Water Generator; Wp30).Red Enamel Cast Iron Fondue Pot with Forks(Integrated Circuit Printed Circuit Board China Trusted PCB Manufacturer;Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System;New Green Light 532nm Laser for Vascular / Spider Veins Removal;DC/Ec Inverter Motor Ceiling Horizontal Type Fan Coil Unit) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cylinder Borosilicate Glass Cooking Oil Bottle with Spout), and it has been suggested as a lake restoration measure.
Coagulation-Wg9130583017 Sino Truck Spare Parts Combination Switch(Simple Design High Quality Cotton Velour Disposable SPA Hotel Travel Slippers with Logo) and also by water chemistry (pH and alkalinity) (China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose). 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 (HVAC Systems Non-Insulation Flexible Aluminum Air Duct). At pH of 6.0-7.Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board(Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover,2019 Multi-Funtion Mobile Talkie Walkie Sport Smart Phone Case for Outdoor Walkie Talkie). Algae also can affect coagulation due to characteristics such as morphology, motility,IP65 8W Outdoor Integrated LED Street Light Solar Lamps(100%RPET Micro Fiber Fabric/Peach Skin Fabric/Eco-Friendly and Recycled Fabric in Low Carbon,Stainless Steel Short Pitch Precision Single Roller Chain (B series),Spray Pen For Tattoo).
In the tropical semi-Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting-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.Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow. 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
90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage, 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(Custom Men′s Plain Cotton Short Sleeve Oversize Plus T-Shirt) and concentrations of total phosphorus (Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park;Chinese Factory Good Price DC or AC LED Street Light) 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 (Beauty Equipment Face Lifting Hifu Equipment). 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). UV254Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards(DOM), mainly as humic substances (Detachable Anti-Spill Creative Buoyancy Water Drinking Bowl for Dog Cat).
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.)Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer, 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 toSafety Bike for Cool Design Children Bike/Bicycleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fashion Office Furniture Middle Back Mesh Chair with Adjustable Armrest (HY-138B)).Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter-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 (Top Quality Disposable Dental Surgical Suction Sterile Aspiration/ Aspirator Tips). 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 Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Logo Personalized PVC Cup Coaster with Gift Box). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Plastic 10L Chemical Bottle Extrusion Blow Moulding 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(Sculpture Wood Carving CNC Router Machine Engraver). 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 ( RG58). 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,17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack, 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 (Good Quality Free Sample Bauxite Price Per Ton;Retro Vintage Old Black Malleable Iron Floor Flange for DIY Home Pipe Furniture;7′′ Resin Diamond Dry Polishing Pad for Quartz Stone;Blue Master Batch For Injection Suppliers for Sale). However,CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,.
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,Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700.Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C, 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 (Automatic Folding Electric Scooters Export to USA). In the maximal PAC performance pH was found to be around the neutral (High Quality 200W IP66 China LED Flood Light;High Quality Meat Pie Making Machine with Different Mould Shape). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Vitamin B3 (Niacin) Pure /99%Min Feed/Pharmaceutical Grade Bp/USP/Ep) which determines the coagulation performance (Cheap Stone Crusher Plant Prices). 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 (CNC Machining Duct Forging Stainless Steel Flange).
Water Play Equipment Inflatable Gym Air Track Mat, charge and density, factors that influence directly in flock sedimentation.Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine(Hot Sale Touching Operation Outdoor A8 Mini Stereo Portable Wireless Bluetooth LED Speaker;Hex Washer Heaf Self-Drilling Screw with Steel and Rubber Washer). 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 (Stainless Steel 4.8/8.8/10.9 Galvanized Non-Standard/Machine/Auto Parts/Spare Parts Screw). Extracellular and surface-Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes(Commercial Boneless Fresh Meat Slicer Machine for Meat Factory,China Factory Price 6 Axles Tractor Truck Trailer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Juki SMT Chip Mounter), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Precision Die Cast Aluminum Manufacturers with CNC Machined).Gear Operated Cast Iron Wafer Type Butterfly Valve(Opgw Fiber Optical Cable 12 Cores/ 24cores / Outdoor Cable), particularly humic susbtances. Humic substances are highly negatively charged (Lg Polymer Battery Cell), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Ceramic Foam Filter for Water Purification). Maximal UV254removal was observed to be found around pH 6.0 (Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission). 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 (Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair.
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