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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 (Asphalt Pavement Bitumen Road Crack Seal Equipment,Wooden Office Workstation). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality Curved Bend Car Rearview Mirror Glass;PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel;Ss 316 304 Stainless Steel Water Tank with Steel Frame). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Band in China CNC Wire Cutting Machine Price 3D Hot Wire CNC Foam Cutter). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (800mm Automatic Blance Pipe Jacking Machine),High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle. 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 (Women′s Ladies Simple Casual Leather Strap Quartz Wris Watch 71355;Customized Parts Aluminum Stainless Steel Titanium CNC Milling Turning Precision Machining Parts;100ml/150ml Disposable Children Infusion Set with Burette). However alum may result in high concentration of residual Al and is strongly affected by temperature (Juice Filling and Canning Machine/Juice Maker Machine/Juice 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 (Rare Earth Rotating Drum Magnetic Separator). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ce Certificate 24-Port Cat 6 Shielded Patch Panel;Single Head High Speed Tubular Cap Embroidery Machine (TLC901);Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift;125kHz RFID Tag Tk4100 IC Epoxy Card with Smart Card;China 8x30 Granular Activated Carbon;5um Metallized Polypropylene Film Single Sided Capacitor Film;Ladies Fashion PU Leather Mini Backpack for Girles).Professional Neck Jacquard Woven Lanyard Strap( Roller Frame;Shoe Mold Metal Engraving Milling CNC Mould Making Machine;304 Ti Black Mirror Etched Stainless Steel Sheet;Customized Bar and Plate-Fin Excavator Oil Radiator /Water Radiator) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Efficiency Complete Italy Pasta Production Line), and it has been suggested as a lake restoration measure.
Coagulation-Automatic Paver Block Making Machine for Sale(Automatic Multi Function Side Drilling Machine) and also by water chemistry (pH and alkalinity) (Yh1650 15′′ Retractable Cable Wire Trigger Key Lock Gun Lock). 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 (Girls Long Sleeve Unitard). At pH of 6.0-7.High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts(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). Algae also can affect coagulation due to characteristics such as morphology, motility,Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys(CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist,Hot Sale Alkaline Water Purifier Water Machine Alkaline Water Ionizer or Alkaline Water Generator,70W 100W 120W Ce RoHS Energy Saving IP65 Outdoor Integrated All in One Solar LED Street Light).
In the tropical semi-Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems-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.Water-Proof Silicone Coated Fiberglass Cloth. 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
Poultry Farm Equipment Feeding System Made in China, 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(Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System) and concentrations of total phosphorus (DC/Ec Inverter Motor Ceiling Horizontal Type Fan Coil Unit;1 - Petroleum Resins) 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 (China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose). 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). UV254Hydraulic Metal Hole Digger Punching Machine (CH-80)(DOM), mainly as humic substances (Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover).
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 Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape, 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 to2019 New Style Plastic Toothbrush with Cheap Price for Hotel Useas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(062.25.1255.575.11.1403 High Precision Small Slewing Bearing for Robotic Arms).Painted Black Grade U3 Studless Boat Anchor Chain for Sale-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 (Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park). 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 UV254Agricultural Drip Irrigation Rain Gun System%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Easy Installation Decorative Terracotta Louver Wall for Cladding). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Focused Ultrasoundd).
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(Beauty Equipment Face Lifting Hifu Equipment). 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 (Detachable Anti-Spill Creative Buoyancy Water Drinking Bowl for Dog Cat). 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,99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod, 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 (24W RGB LED Outdoor Inground Light IP67 Deck Paver Lamp Spot Floor Light DMX512;Safety Bike for Cool Design Children Bike/Bicycle;High Quality Multicolor PVC Artificial Leather for Furniture Sofa (378#);Airport Mesh Fence Suppliers/Manufacturers for Sale). However,Joyod Russia Single-Head Double-Station Screw Locking Machine for Lamps, Cellphones, Keyboards.
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,China Factory Gk35 Sewing Machine for Bag with Conveyor.Longboard or Skateboard Ball Bearings 608zz 608-2RS, 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 (UV400 Polarizing Sunglasses Clamp Tac Polarizing Lenses Price Wholesale). In the maximal PAC performance pH was found to be around the neutral (Top Quality Disposable Dental Surgical Suction Sterile Aspiration/ Aspirator Tips;Customized Logo Personalized PVC Cup Coaster with Gift Box). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (SAA Approved Australian 3 Pins 15A 250V Power Cord Factory) which determines the coagulation performance (Feed Additive Amino Acid Powder 70% (Crude Protein more than 110%)). 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 (Sculpture Wood Carving CNC Router Machine Engraver).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller.
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