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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 (Plumbing Fitting Water Connect Black Surface 1/2 Malleable Iron Flat Seat Conical Union,Drawstring Sports Bag). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Male Female Screw Fasteners Connecting Book Screws;Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191;Multipurpose Rutile Titanium Dioxide TiO2 Pigment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Contemporary Art Modern Wall Decor Giclee Artwork 3 Piece Canvas Print). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Australian AC Power Cord with SAA Certfication Plug and C13 Connector),Fresh Mung Bean Filling Stand-up Pouch Packing 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 (Fast Inflatable Air Bag Sofa Lounge Lazy Chair Bag Camping Bed Beach Hangout;Dr3008 Male&Female NPT Swivel Type Metal Brass Ferrule Valves;Bzw-2W Bozwang Shield Net Combing Device Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Factory Direct Sale Warehouse Light IP65 150W LED High Bay) 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 (Mobile Nfc Sticker High Quality Supplier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses;Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent;Wire to Board Spring Type Connector Sy141-2.54mm Made in China;High Speed PVC Extrusion for Insulation Electrical Wire House Wire;Dichroic Glass Cabochons Jewelry Findings;Fancy Personalized Charm Simple Crown Trendy 925 Sterling Silver White Gold Bracelet;5X5m Aluminum High Peak Gazebo Pagoda Tent for Events).Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order(PVC Coated Galvanized 12 Guage Iron Baling Wire;PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence;Sandwich Roofing;Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood), and it has been suggested as a lake restoration measure.
Coagulation-Newest Robot Vacuum Cleaner with GPS, Camera, Built-in Virtual Wall(Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels) and also by water chemistry (pH and alkalinity) (Hot Selling Wireless Cell Phone Charger for Android Ios). 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 (240mm Grinding Wheel). At pH of 6.0-7.Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV(Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring,Cheaper Polyester Cord Strap Factory Made in China). Algae also can affect coagulation due to characteristics such as morphology, motility,1616 Aluminum LED Strip Channel Surface Mount LED Extrusion(AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine,Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment,Kidney Stress Ball).
In the tropical semi-600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag-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.Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce. 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
High Pressure Zirconia Ceramic Piston Rod Pump Ceramic, 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(Good Price and High Quality Crawler Crane Excavator Bearing) and concentrations of total phosphorus (Three Layers ABC Co-Extrusion PP Film Blowing Machine;Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine) 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 (Kaishan YT23D Forging Air Leg Support Rock Drill Machine). 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). UV254Brown Shoes High Quality Strong Protection Working Shoes(DOM), mainly as humic substances (High Polished Solid Egypt Sunny Beige Marble Columns).
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.)700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346), 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 toNew Design Brass IP68 LED Underwater Fountain Lightas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Lao Ban Beancurd).4we5 Electrically Operated Directional Control Valves-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 (2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger). 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 UV254Single Head High Speed Tubular Cap Embroidery Machine (TLC901)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM Production Fancy Folding Paper Window Gift Boxes). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Customized Label For Jewelry Factory OEM/ODM Productsd).
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( Tiger Skin Yellow Cement Based Wall Stone Veneer). 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 (Watertight Hi-Viz Yellow Thermal Latex Gloves Safety Work Glove). 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,Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System, 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 (Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog;HDF Mould Skin Doors Wooden with Cheap Prices for Kid Rooms;Easy Maintenance Automatic 6000PCS/H Egg Tray Machine;Small Spiral Binding Machine). However,High Speed LDPE Polyethylene Plastic Film Extrusion Machine.
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,Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event.Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe, 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 (New selling OEM quality strong magnet segment arc ferrite magnet for motor). In the maximal PAC performance pH was found to be around the neutral (Low Price 10mm 210rpm Small Speed Reducer Gearbox;LED Car Work Light of 51W 6inch with off-Road Spot Beam). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (50-500μ M Pet Film for Electrical Insulation (6023D)) which determines the coagulation performance (boat hitch coupler locking pin). 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 (Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder).
Caprolactam Grade Ammonium Sulphate (21%Min), charge and density, factors that influence directly in flock sedimentation.Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm(Color Shifting Chameleon Pigment for Car Paint Factory;Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet). 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 (Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe). Extracellular and surface-NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor(Basic Plain T-shirts,18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material), which can be one important cause of the increase in coagulant demand in algae-rich waters (LSR Injection Mold Tooling for Medical Nipple).Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles(High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing), particularly humic susbtances. Humic substances are highly negatively charged (2019 Hot Sale High Quality Men′s Workwear Softshell Waterproof Jacket with Reflective Piping), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)). Maximal UV254removal was observed to be found around pH 6.0 (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw). 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 (Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment.
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