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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 (Dr3008 Male&Female NPT Swivel Type Metal Brass Ferrule Valves,Child Folding High Chair). As a result, several chemical methods have been applied to control P internal loading worldwide (Bzw-2W Bozwang Shield Net Combing Device Machine;Factory Direct Sale Warehouse Light IP65 150W LED High Bay;Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Agricultural Rotary Disc Mower, Grass Cutting Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (380v Water Cooling Electric Motor),Dk7725b New Condition Wire EDM Electrical Discharge Machine. 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 (Wire to Board Spring Type Connector Sy141-2.54mm Made in China;High Speed PVC Extrusion for Insulation Electrical Wire House Wire;Fancy Personalized Charm Simple Crown Trendy 925 Sterling Silver White Gold Bracelet). However alum may result in high concentration of residual Al and is strongly affected by temperature (5X5m Aluminum High Peak Gazebo Pagoda Tent for Events) 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 (Silver Rhinestones). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (PVC Coated Galvanized 12 Guage Iron Baling Wire;PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence;Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle;Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood;Frp Anchor Rod;Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels;Hot Selling Wireless Cell Phone Charger for Android Ios).Porcelain Custom Logo Ceramic Tiki Cup Mug(Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring;Cheaper Polyester Cord Strap Factory Made in China;Sinotruk HOWO 6*4 10 Wheelers 371HP Diesel Heavy Duty Tow Tractor Truck Head;AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Biometric Fingerprint and RFID Card Access Control Reader Sf1(Special Flower Shaped Sterling Silver Cubic Zirconia Earring for Lady Wedding Gift) and also by water chemistry (pH and alkalinity) (CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling). 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 (Modern Double Bed bedding Design Hotel Bedroom Furniture Set). At pH of 6.0-7.Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer(Good Price and High Quality Crawler Crane Excavator Bearing,Three Layers ABC Co-Extrusion PP Film Blowing Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test(Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass,Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm,Asset Inventory Management Heat Resistant UHF RFID Anti Metal Tag).
In the tropical semi-Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock-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.Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress. 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
Surgical Instrument Rife High Frequency Welding Machine Me-50A, Skin Care, 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(Multi-Functional Universal Mount LED Brake/Turn/Tail Lights) and concentrations of total phosphorus (Natural Color of 100% 7A Malaysian Human Hair;2.54 Pitch Male Pin Header Board to Board Power Connection Electronic PCB Board Connector) 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 (Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer). 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). UV254Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh(DOM), mainly as humic substances (China Supplier Seamless Carbon Steel Pipe for Motorcycle Parts with 1010).
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.)Soft Touch 22 Inch Reborn Silicone Baby Doll Kits, 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 to Tiger Skin Yellow Cement Based Wall Stone Veneeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(4m Folding Handle Manual Hydraulic Electric Scissor Lift).2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine-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 (Android Handheld Barcode Scanner Industrial PDA). 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 UV25434mm 7 Grade Atlas Copco Marble Gauge Rock Drill Parts Tapered Button Bit%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (8000lbs Pull DC 12V Electric Winch with Wire Roped).
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(Easy Maintenance Automatic 6000PCS/H Egg Tray 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 (New selling OEM quality strong magnet segment arc ferrite magnet for motor). 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,NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M), 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 (50-500μ M Pet Film for Electrical Insulation (6023D);Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder;Color Shifting Chameleon Pigment for Car Paint Factory;Belt Conveyor Steel Impact /Trough/Troughing/Carrier/Carrying/Return Guide Idler Roller 51). However,OEM Chinese Factory Stainless Steel Flanged Gate Valves.
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 Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier.Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve, 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 (Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet). In the maximal PAC performance pH was found to be around the neutral (Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe;18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material) which determines the coagulation performance (TM32 Series Supplier). 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 (LSR Injection Mold Tooling for Medical Nipple).
Bzw-2W Bozwang Shield Net Combing Device Machine, charge and density, factors that influence directly in flock sedimentation.1325 High Quality Steel Aluminum Metal Plasma Cutting Machine(High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing;Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)). 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 (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw). Extracellular and surface-Sle4442 hotel key card PVC blank contact RFID card(Travel Box Case Holder Fit for Philip Oral Irrigator,Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Private Label Washing Laundry Powder Detergent), which can be one important cause of the increase in coagulant demand in algae-rich waters (New Product 2019 Milky White Electrochromic Smart Film).100ml/150ml Disposable Children Infusion Set with Burette( Transparent Acrylic Double-Sided Tape), particularly humic susbtances. Humic substances are highly negatively charged (Tungsten Crucible and Tungsten Tube Tungsten Copper Alloy), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Fashion Design Steel-Wood Large Conference Table). Maximal UV254removal was observed to be found around pH 6.0 (Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet). 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 (Easy to Use Mobile Filter Unit for Light to Medium Welding).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.20% White Vinegar Available for Agricultural or Cleaning Purposes.
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