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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 (Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses,Inflatable Saturn Rocker Water Park Play Equipment for Lake or Sea). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fancy Personalized Charm Simple Crown Trendy 925 Sterling Silver White Gold Bracelet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,30% Al2O3 Content Yellow PAC for Wastewater Treatment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (jb-hardware.com),Hydraulic Press Machine Deep Drawing Press 100 Ton. 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 (5X5m Aluminum High Peak Gazebo Pagoda Tent for Events;PVC Coated Galvanized 12 Guage Iron Baling Wire;PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence). However alum may result in high concentration of residual Al and is strongly affected by temperature (Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle) 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 (Cooking Utensils Set). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood;Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels;Hot Selling Wireless Cell Phone Charger for Android Ios;Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring;Nylon Insert Nuts;Cheaper Polyester Cord Strap Factory Made in China;AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine).Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date(Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment;Special Flower Shaped Sterling Silver Cubic Zirconia Earring for Lady Wedding Gift;Ductile Iron Wafer Type Single Disc Swing Check Valve;CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Price and High Quality Crawler Crane Excavator Bearing), and it has been suggested as a lake restoration measure.
Coagulation-High Carbon Steel Wire Lead Patenting Phosphate Production Line(Three Layers ABC Co-Extrusion PP Film Blowing Machine) and also by water chemistry (pH and alkalinity) (Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass). 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 (Led Acrylic Letters Factory & Manufacturer). At pH of 6.0-7.Furniture Laminate Sheet/HPL Panel/Building Material(Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm,Kaishan YT23D Forging Air Leg Support Rock Drill Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Woodworking Machine One Head Economic Model CNC Router(High Polished Solid Egypt Sunny Beige Marble Columns,Multi-Functional Universal Mount LED Brake/Turn/Tail Lights,Collagen Dietary Supplement).
In the tropical semi-Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event-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.Customized EPDM NBR Rubber Bellows Expansion Joint. 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 Speed 6 Color PP Woven Bag Printing Machine, 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(New Design Brass IP68 LED Underwater Fountain Light) and concentrations of total phosphorus (Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer;plated badge) 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 (OEM Production Fancy Folding Paper Window Gift Boxes). 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). UV254Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform(DOM), mainly as humic substances (Toroidal Power Transformer for Household Audio).
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.)E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits, 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 toAndroid Handheld Barcode Scanner Industrial PDAas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wholesale Empty Perfume Bottle 10ml Cosmetic Roll on Bottle).1.2mm Thick Faux Suede Backing Shoes Leather Fabric-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 (Easy Maintenance Automatic 6000PCS/H Egg Tray Machine). 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 UV254dual Row 15pin D-SUB Mechined PCB Mounting Power Connector%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New selling OEM quality strong magnet segment arc ferrite magnet for motor). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Wholesale Price CPE Power Cable Flexible Mining Cabled).
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(LED Car Work Light of 51W 6inch with off-Road Spot Beam). 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 (50-500μ M Pet Film for Electrical Insulation (6023D)). 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,Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting, 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 (Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet;Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe;18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display;Microfiber Like Suede Leather). However,48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel.
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,Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon.Factory Supply Cheap Custom Bleached White Cotton Gloves, 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 (18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material). In the maximal PAC performance pH was found to be around the neutral (LSR Injection Mold Tooling for Medical Nipple;High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)) which determines the coagulation performance (Carbon Steel Pipe Fittings). 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 (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw).
ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling, charge and density, factors that influence directly in flock sedimentation.High Polished Solid Egypt Sunny Beige Marble Columns(Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag;Private Label Washing Laundry Powder Detergent). 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 (New Product 2019 Milky White Electrochromic Smart Film). Extracellular and surface-CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling(High Quality Long Life Durability Use Steel Nipper Combination Pliers, Transparent Acrylic Double-Sided Tape). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Fashion Design Steel-Wood Large Conference Table), which can be one important cause of the increase in coagulant demand in algae-rich waters (Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet).RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm(Easy to Use Mobile Filter Unit for Light to Medium Welding), particularly humic susbtances. Humic substances are highly negatively charged (New Fitness Commercial Exercise Spinning Bike), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line). Maximal UV254removal was observed to be found around pH 6.0 (Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use Machine). 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 (Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top.
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