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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 (Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System,Hologram Void Sticker). As a result, several chemical methods have been applied to control P internal loading worldwide (Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm);Factory Nitrogen Fertilizer Ammonium Sulphate 21%N Steel Grade for Agriculture;OEM Chinese Factory Stainless Steel Flanged Gate Valves). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Stainless Steel CNC Machining Parts Watch Case). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Power/Torque Density 7.5kw 2500rpm AC Servo 3 Phase Motor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Gainswave Shockwave Therapy Physiotherapy Device),L Sealing Automatic Egg Tray Heat Shrink Wrapping Packaging 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 (Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator;Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden). However alum may result in high concentration of residual Al and is strongly affected by temperature (12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price) 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 (www.xcfrfpc.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor;Multi-Functional Toys Packaging Machine for Packaging of Children Toys;Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide;Tubular Polyethylene Plastic Film Blowing Machine;High Quality Mirror for KIA Picanto Morning 2012-2013. Factory Directly. 87610-1y260/87620-1y260;Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside;G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine).925 Fashion Silver Heart Earrings Stud Simple for Sale(800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller;Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS;Anti Dust Bio Sponge Filter;PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle), and it has been suggested as a lake restoration measure.
Coagulation-Cheap Soccer Game Table Foldable Football Table with L Shape Leg(Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed) and also by water chemistry (pH and alkalinity) (16 Strings Solar Power Equipment Combiner Box for 1000V DC System). 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 (Ceramic Rubber Lining). At pH of 6.0-7.Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale(Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay,Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike). Algae also can affect coagulation due to characteristics such as morphology, motility,Electrically Heat Furnace Prime Quality Radiant Tubes(Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China,4.8X1.2m Autoclaved Aerated Concrete Production Line,Arabic Floor Polished Tile 600X600 Black White Stripe Marble Stone).
In the tropical semi-Hot Sale Men Injection Casual Shoes Sport Running Sneaker Shoes 9319-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.2800X8000mm ASME Certified Rubber Vulcanizating Chamber (SN-LHGR2880). 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
2 in 1 Baby Feeding Chair Kids Eating High Chair, 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( Mate20 PRO Pantalla Display) and concentrations of total phosphorus (High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape;608rs Bearing) 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 (Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R)). 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). UV254Lifting and Hoisting Industrial Manual Chain Lever Block Vt(DOM), mainly as humic substances (Promotion Custom Polyester Lanyard Strap with Metal Hooks).
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.)Galvanized Pullet Chicken Cage Baby Chicken Cages, 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 toOEM Large Diameter Aluminum Curtain Wall for Building Materialas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Promotion Digital Printing Garment Fabric Fashion Shirts for Men Tshirt).Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection-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 (1390 Mixed CO2 Laser Cutting Machine for Wood Acrylic MDF Stainless Steel Carbon Steel Plywood Cut). 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 Full Series Extruded Aluminum Profile for Kitchen%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Portable Solar Lantern with Built-in Solar Panel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Professional 2 Stroke New Design Engine 50.8cc Farm Cultivatord).
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(7 Color LED Facial Mask Neck Mask LED Photon Mask for Skin Care). 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 ( Cargo Box). 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,Stainless Steel Short Pitch Precision Single Roller Chain (B series), 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 (Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather;Excellent Quality High Effciency Pop Can Bottle Filling Machine;HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage;Adjustable COB Spotlight LED Track Light 30W 6500K Cool White). However,18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material.
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,Chinese 1kw Vertical Axis Wind Turbine for Home Use.Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic, 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 (High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings). In the maximal PAC performance pH was found to be around the neutral (Electric Hand Circular Saw for Wood Cutting 185mm;Quality Assurance Refillable Nitrogen Gas Cylinder). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (4 Port FTTH Splice Box for Optic Fiber Termination and Sc Connection) which determines the coagulation performance (Yn27c Petrol Air Leg Rock Drill with Gasoline Power). 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 (48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers.
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