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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 (Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas,Heart Shaped Perfume). As a result, several chemical methods have been applied to control P internal loading worldwide (0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal;Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer;Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ac Servo Motor),Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label. 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 (Promotional Safety Products D160 Hang Reflectors;Porcelain Custom Logo Ceramic Tiki Cup Mug;IC ID Epoxy Tag Entrance Guard Card Key Fob for Elevator Property Management). However alum may result in high concentration of residual Al and is strongly affected by temperature (2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available) 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 (19- Inch Floor Standing Internet Touch Screen Advertising Display Kiosk). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Aluminum Hard Equipment Gift Flight Case for Guitar;12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch;Eco Recycled Kraft Paper Box for Salad and Lunch;C6251 lathe machine specification gap bed lathe machinery universal lathe machine;18mm Concrete Shuttering Plywood Board;Portable for Mobile 120W 24V Automatic Car Key Cutting Machine;Delivery Cylinder Used in Concrete Pump Truck for Construction).8.8ah, High Production Efficiency Skateboard(Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips;Black Shelf Table Storage Basket Rack Kitchen Wire Mesh Cabinet Organiser;Food Digital Thermometer;Rope and Net PP Filament Yarn Extruding Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Smart Electronic RoHS Weighing Scale PCB Manufacturer with Fast Delivery(Building Construction Decoration Material Aluminum Plastic Composite Panel) and also by water chemistry (pH and alkalinity) (Low Factory Price UHP Graphite Electrode Used for Steel Making). 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 (UPVC Pn10 DIN Equal Reducing Female Tee with Brass for Water Supply Fitting). At pH of 6.0-7.12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools(Jy-616 Conference Plastic Auditorium Chairs with Cup Holder Cinema Seating,AC 24V 400W Verical Axis Wind Turbine (SHJ-NEV400S)). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover(Top Quality Outdoor Granite Water Fountain for Garden Decoration (GSF-104),Double Sphere Air Release Valve Automatic Air Release Valve,160cm New Model TPE Silicone Sex Doll Man Masturbation Love Doll).
In the tropical semi-Stainless Steel Extruder Screen Packs/Filter Screen Packs/Circular Mesh Screen-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.Optical Solar Smoke Detector with Testing Button (ES-T601). 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
Steel Wire, Security Protected Razor Barbed Wire/Blade Barbed Wire, 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(Give More Muscle Ghrp-6/Ghrp6 Peptides Good for Aiding Fat Loss) and concentrations of total phosphorus (Portable Facial Skin Scrubber Scraper Machine for Beauty Care;Dc Powered Speakers) 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 (Tungsten Carbide Cold Heading Dies for Screws and Nuts). 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). UV254Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush(DOM), mainly as humic substances (Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker).
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.)Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding 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 toNo Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcheras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Vvvf Control High Speed Golden Etching Home Villa House Lift).Automatic White Cardboard Paper Roll to Sheet Cutting 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 (V4 Type Sintered Porous Filter with Female Thread). 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 UV254Kids Electric Car with 12V Battery Remote Control%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (PVC Stripe Anti-Slip Door Mat with Color 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 (Before Sewing Machine Series Round Knife Cutting Machine Bb65d).
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(Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400). 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 (Hydraulic Scrap Metal Baling Machine for Metal). 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,300bar High Pressure Air Compressor with Capacity of 100~500L/Min, 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 (The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta;Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom;New Product Ideas Wooden Musical Jewelry Storage Box;Private Label Waterless Hand Gel Pk3 Portable Hand Sanitizer Gel). However,3.5mm, 4.5mm PVC Floor Wooden Color Flooring Plank.
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,OEM Manufacturer 6 Rolls Shrink Pack BOPP Crystal Tape.Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine, 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 (21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult). In the maximal PAC performance pH was found to be around the neutral (Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery;Large Music Controlled Colorful Laser Water Fountain). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil) which determines the coagulation performance (Water Evaporative Air Cooler for Industry). 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 (1/2 CRV Industrial High Quality Quick Release Ratchet Handle Wrench).
Dia120mm*120mm Casting Swivel Anchor Nut for Formwork and Scaffolding Accessories, charge and density, factors that influence directly in flock sedimentation.Hot Sale Jumbo Roll Double Sided Adhesive Tissue Tape for Cars (DTS10G-15)(Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal;SKF NTN Chik Koyo Deep Groove Ball Bearings 6308 Zz Ball Bearing Turbo for Sale 40*90*23mm). 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 (Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof). Extracellular and surface-Classical Gym and Commercial Fitness Equipmen Decline Bench T40(Siboasi S4025 High Quality Programmed Badminton Machine with Free Battery,5r 200W LED Moving Head Beam 3 in 1 Stage Lighting). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price), which can be one important cause of the increase in coagulant demand in algae-rich waters (Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel).80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO(Hybrid Power System 150kw Electricity Generating System with Battery Bank), particularly humic susbtances. Humic substances are highly negatively charged (Pu Coating), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Customzied SKD11 Shear Blades for Leather and Plastic). Maximal UV254removal was observed to be found around pH 6.0 ( Keyboards). 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 (10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-Holder.
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