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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 (15mm Thickness Industrial NdFeB Rare Earth Magnet,Solar Rechargeable Li-ion Batterylifepo4 Lithium Battery for Energy Storage Application). As a result, several chemical methods have been applied to control P internal loading worldwide (Ldd-100 High Efficient Electric DTH Drilling Machine;Gold Supplier Deep Groove Ball Bearing 6311 P5 6204zz 6204 Ball Bearing Ball Bearing 6204 6204 C3;Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Desktop Fiber Laser Marking Machine with Computer Price $3300). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Factory Supply Raw MDF / Melamine Faced MDF Plain MDF with Cheap Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Optical Fiber Pigtail for 12 Core Sc/APC Cable with Fast Delivery),Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing 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 (Compatible Quality Handy Color Jumbo Stretch Cling Film;China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine;Solar Power Refrigerator 12V DC Mini Fridge). However alum may result in high concentration of residual Al and is strongly affected by temperature (19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen) 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 (Amusement Park Theme Park Aquatic Equipment Fiberglass for Combine Slide). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Contec Cms-Vesd Digital Multi-Functional Visual Stethoscope with SpO2/Estetoscopio;Asphalt Pavement Bitumen Road Crack Seal Equipment;High Quality Curved Bend Car Rearview Mirror Glass;PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel;Air Riveter High Quality Supplier;Ss 316 304 Stainless Steel Water Tank with Steel Frame;Best Band in China CNC Wire Cutting Machine Price 3D Hot Wire CNC Foam Cutter).Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer(Women′s Ladies Simple Casual Leather Strap Quartz Wris Watch 71355;Customized Parts Aluminum Stainless Steel Titanium CNC Milling Turning Precision Machining Parts;7 Day Candle Glass Wholesale;100ml/150ml Disposable Children Infusion Set with Burette) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Juice Filling and Canning Machine/Juice Maker Machine/Juice Machine), and it has been suggested as a lake restoration measure.
Coagulation-Hot Sale Copolymer Coated Aluminum Foil Tape for Cable(Ce Certificate 24-Port Cat 6 Shielded Patch Panel) and also by water chemistry (pH and alkalinity) (Single Head High Speed Tubular Cap Embroidery Machine (TLC901)). 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 (Wholesale OEM Draw String Patterned Black 100%Cotton Yoga Fitness Running Sport Hoodies). At pH of 6.0-7.Customized Stainless Steel CNC Machining Parts Watch Case(Mobile Scissor Lift Underground Car Lift/ Hydraulic Car Lift,125kHz RFID Tag Tk4100 IC Epoxy Card with Smart Card). Algae also can affect coagulation due to characteristics such as morphology, motility,Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker(5um Metallized Polypropylene Film Single Sided Capacitor Film,Ladies Fashion PU Leather Mini Backpack for Girles,1 Micron Nonwoven Needle Punched Felt Polypropylene Filter Cloth).
In the tropical semi-Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration-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.Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333. 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
Tungsten Carbide Milling Insert for Book Binding, 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(Customized Bar and Plate-Fin Excavator Oil Radiator /Water Radiator) and concentrations of total phosphorus (High Efficiency Complete Italy Pasta Production Line;Top Quality High Strength Magnetic Force Dry Fine Powder Electromagnetic Separator) 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 (Hot Selling Mini Am RF Security Hard EAS Pencil Tag for Clothing Store). 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). UV254Double Side Painted Aluminium Coil Plate with PE Film(DOM), mainly as humic substances (7.00-20 Tube Rim TBR Truck Steel Wheel with TS16949/ISO9001: 2000).
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.)Professional Double Cup Fully Automatic Coffee Machine, 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 toIntegrated Circuit Printed Circuit Board China Trusted PCB Manufactureras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bobbin Fibre Paper Making Press Felt Fabic Clothing).Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels-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 (Cylinder Borosilicate Glass Cooking Oil Bottle with Spout). 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 Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Simple Design High Quality Cotton Velour Disposable SPA Hotel Travel Slippers with Logo). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Abs Trolley Luggagesd).
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(Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover). 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 (2019 Multi-Funtion Mobile Talkie Walkie Sport Smart Phone Case for Outdoor Walkie Talkie). 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,Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric, 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 (2019 New Style Plastic Toothbrush with Cheap Price for Hotel Use; Solvent PVC-Free Wall Paper;Custom Men′s Plain Cotton Short Sleeve Oversize Plus T-Shirt;Laser Cutting Machine Steel). However,Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17.
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,Low Price Promotional Concrete Cement Mortar Plaster Pump Machine.18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display, 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 (Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park). In the maximal PAC performance pH was found to be around the neutral (Easy Installation Decorative Terracotta Louver Wall for Cladding;Industrial Use Sandwich Panel Container for Offices/Construction Sites). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Beauty Equipment Face Lifting Hifu Equipment) which determines the coagulation performance (Architectural Mesh). 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 (Detachable Anti-Spill Creative Buoyancy Water Drinking Bowl for Dog Cat).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Drying Efficiency Wood Sawdust Dryer for Sale.
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