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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 (8mm PVC Coated Galvanized Steel Wire Rope for Lifting,Door Handle On Plate). As a result, several chemical methods have been applied to control P internal loading worldwide (Manufacture RP HP UHP Graphite Electrode 300mm 350 with Nipples for Smlting;Good Quality UPS Batteries 12V 65ah for Burglary Protection System;Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Touch Screen for iPhone 6s LCD Touch Screen Digitizer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ems Slimming Machine),Automatic Folding Electric Scooters Export to USA. 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 (Wholesale Events 6FT Wood Dining Round Table; Wall Fan 3 in 1-Competitive Price;CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws) 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 (m.alsichina.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale;Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition;(Made in China gold sellers) SPA Swimming Pool Water Filter Pump;Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board;Bamboo Toothbrush Natural Organic Biodegradable and Vegan Bamboo Soft BPA Free Nylon;Stainless Steel SS304 and SS316 Closed Body Turnbuckle;OEM Fabric Adjustable Bike Baby Stroller Feeding Feed Bottle Cup Holder).Ceramics, Porcelain &Enamal Plate Bowl and Cup(Gondola Supermarket Shelf Candy Shelf for Confectionery Equipment;Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch;Granulated Ice and Snow Melting Salt for Road/Highway/Airport;250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)), and it has been suggested as a lake restoration measure.
Coagulation-28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket(Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve) and also by water chemistry (pH and alkalinity) (Customized Non-Standard Machinery Part CNC Aluminium Machining CNC Metal Milling Service). 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 (Cheap Price Fun Used Indoor Kids Climbing Wall). At pH of 6.0-7.Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester(Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack,Disposable Plastic PE Icing Piping Cake Decorating Pastry Bag Making Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine(20A 12/24V Auto Intelligent LCD Solar Panel Charge Controller (QWP-SR-HP2420A),Hot Sale Outdoor Car Carport Shelter with Low Price,3 Strand 8strand 12 Strand Polypropylene (PP) Rope Mooring Rope for Ship).
In the tropical semi-Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens-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.CNC Forging Motorcycle Aluminum Chain 520 Sprocket. 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
Welding Turning Roll for Pipe Welding Hdtr-1000, 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(Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery) and concentrations of total phosphorus (Automatic CNC Pipe Beveling Machine with Three Servo Motor (TEF508CPV);YTO 1254 Farm Tractor for Sale with Attachments Disc Harrows) 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 (Br42 Red Color Mushroom Head Push Button Switches). 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). UV254Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen(DOM), mainly as humic substances (High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design).
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.)Cheap China 2 Inch Wafer Stainless Steel Butterfly Valve, 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 toWholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Yanmar 10kw Engine Mini Excavator Mini Digging Machine Qtp12).Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO-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 Fan Lashes Blooming Lashes Volume Eyelashes Extension). 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 UV254Ss Wire Mesh Heat Resistant Wire Mesh Conveyor Belt%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Single Phase Frequency Inverter AC Motor Speed Controller 250000W). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cement Use Pva Fiber Manufacturers Cheap Priced).
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(Dienedione Raw Powder Estra-4). 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 (Modern 60W Glass Table Lamp for Office Bedroom Home Decor). 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 Checkered Plate 304 316L 410 Floor Material, 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 (5FT2′ 157cm Female Premium Platinum Silicone Love Doll Lifelike Adult Love Sex Toy for Men;Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb;8.8ah;Waterproof Backpack Manufacture). However,Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang 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,Biodegradable PLA Film for Food /Fruit Packaging.EU Standard Top Quality Portable Indoor Playground Equipment, 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 (Custom Cheap Design Woven Patch Embroidery Badge). In the maximal PAC performance pH was found to be around the neutral (316L Stainless Steel Pipe Fitting Elbow SMS DIN Elbow;Multi Color Dual Slides Crayon Inflatable Bouncer Castle). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (5053 Aluminum OEM ODM Computer Parts Oxide Anodized CNC Machining Mobile Phone Parts) which determines the coagulation performance (Collapsible Paper Box Foldable Paper Box Gift Packing Box). 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 (Roller Shutter Components Galvanized Octagonal Tube Axle).
61539 Double Handle 4 Inch South American Style Faucet, charge and density, factors that influence directly in flock sedimentation.3mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration(Waterproof Home Decoration Decoration Material WPC Spc Wall Panel;Competitive Prices Gypsum Board). 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 (Factory Direct Sale Hotfix Laser Motif Customer Desgined for Decoration). Extracellular and surface-High Temperature Resistant Industrial Cement PPS Air Filter Bag(1K Byte 13.56MHz Mf Programmable RFID Security Stickers Tags,Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Top Quality Gasoline Grass Trimmer Parts Nylon Head Blade), which can be one important cause of the increase in coagulant demand in algae-rich waters (Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use).Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver(Eco-Friendly Biodegradable Natural Wheat Straw Toothbrush with Bamboo Charcoal Infused Bristles), particularly humic susbtances. Humic substances are highly negatively charged (Egg Tray Pulp Molding Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New 11ml Nail Polish Bottle with Brush and Cap). Maximal UV254removal was observed to be found around pH 6.0 (Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs). 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 (LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015).
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