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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 (1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree),Aluminium Cnc Cutting). As a result, several chemical methods have been applied to control P internal loading worldwide (New Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer;Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection;European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Sesame Almond Cashew Nut Peanut Butter Making Processing Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manufacture Aluminum Outdoor Event Smart Design Truss Stage, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Label Digital Graphic Arts Imaging Printing 540mm Paper Size A4 and A3 Laminating Machine),Zinc-Plated Carbon Steel Tiger Clamp Spiral Double Bolts Clamp. 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 (En10305 Cold Drawn/Rolled Seamless Steel Tube for Hydraulic Tube;Brown Fused Alumina Grain for Abrasive and Refractory;2018 Hot Sell Bathroom Glass and Mirror Accessories). However alum may result in high concentration of residual Al and is strongly affected by temperature (Best Price Semi Automatic Silicone Sealant Filling Sealing Machine) 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 (China Adult Diaper Supplier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (6061 6063 Extrude Aluminum Extrusion Profile Section Supplier;Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat;Universal Cable Fault Testing Instrument Tester / Analyzer;Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer;PE Metallized Protective Film for Aluminium with 10 Years Exprience;Foshan Manufacturer Bathroom Glass Sliding Door Roller;Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding).Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings(SGS Certificate PE Heat Shrink Film for Beer;Sandblast Finish Inside Glass Lampshade with Rod Different Colors Are Available;307a Hex Bolt Factory OEM/ODM Products;Mobile and Prefab House Light Steel Sructure Villa -Made in China) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Yx35-925 Glazed Tile Roll Forming Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Shanghai Port Adjustable Steel Hinge for Security Wooden Door(FDA Natural Banish Hangovers Dihydromyricetin (DHM) 98% HPLC) and also by water chemistry (pH and alkalinity) (Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang Machine). 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 (2.2L Hot Sale PETG BPA Free Plastic Water Bottle with Stainless Steel Lid (HDP-0618)). At pH of 6.0-7.High Quality Watermark Brass Square Bottle Trap in Gold(Automatic Disposable Hotel Supplies Packing Machine Horiaontal Wrapping Machine,Stainless Steel Sheet 254smo). Algae also can affect coagulation due to characteristics such as morphology, motility,PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine(40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale,China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V,Auto Cup Holder).
In the tropical semi-High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns-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.Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032). 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
Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220, 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(Organic Fertilizer Production Line for Manure Treatment) and concentrations of total phosphorus (Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand;Qt8-15 Fully Automatic Concrete Hollow Block Paver Brick Making Machine with Hydraulic Technology) 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 ( VDE). 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). UV254Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier(DOM), mainly as humic substances (Pet Strap Production Line with Good Quality).
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.)Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts, 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 toLaser Cutting Machine 500W 1000W 2000W Fiber Laser Pipe and Tube Cutting Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Steel Plate Wheel Shot Blast Machinery Polishing Machine).Factory Price Resin Wedding Chairs for Sale-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 (3mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration). 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 UV254Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM Hyaluronic Acid Facial Cream Cosmetic for All Skin). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Peanut Machined).
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(PLC Controlled Transfer Cart Rail Drive Steel Platform). 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 (Carbon Steel Lifting Chain Eye Slip Hook with Latch ). 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,Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring, 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 (Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine;Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper; Cookies;Fashion Excellent Quality Full Color Small Quantity Hardcover Book Printing). However,Aluminum/Aluminium Foil for Aseptic Milk Packaging.
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,0.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems.Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046), 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 (7.5HP Centrifugal Circulation Swimming Pool Water Pump). In the maximal PAC performance pH was found to be around the neutral (90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage;SMC / BMC Compression Molds and Molded Parts From China). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (800g ECR Glass Fibre Plain Woven Roving 800GSM for Munal Boats Buildings) which determines the coagulation performance (12V14ah Children Car Battery Sealed Lead Acid Rechargeable UPS Battery). 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 (High Quality Low Price Square Pipe CNC Plasma Cutting Tool).
600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine, charge and density, factors that influence directly in flock sedimentation.2019 New Bio Vacuum Cavitation RF 6 in 1 Fat Freezing Body Slimming Salon SPA Machine(USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer;Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine). 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 (Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids). Extracellular and surface-China Supply Soft and Hard 304 316 Stainless Steel Wire Hot Sale in Amazon(PE Pipe Fitting Flange Stub for Water Supply,Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Tolerance Stainless Steel Stamping Parts Enclosure).Logo Printing Stickers, Customized Fancy Printing Adhesive Paper Label Sticker(3 Inch Smooth Corrugated PVC Suction and Discharge Hose), particularly humic susbtances. Humic substances are highly negatively charged (Hot-Selling Heat Transfer Printed Polyester Ribbon with Custom Logo), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Custom Electronic Wire Harness with Jst Molex Housing Connector). Maximal UV254removal was observed to be found around pH 6.0 (Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip). 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 (Factory Made Cheap Price Latching Circuit Relay for Power Control).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Hf Vacuum Dryer Machine China Supplier.
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