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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 (Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home,Best Selling Silicone Sponge Sheet Cutting Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter;2018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds;Nylon Flashing LED Dog Leash with Night Light). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Aluminium Spigot Lighting Truss). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Building Hot Rolled C Purlin C Channel Steel Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Plastic WPC Floor Panel PVC Foam Board PVC Foam Sheet Extrusion Line Production Line),Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516). 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 (Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032);Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060;Plastic Roofing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Quality Tungsten Carbide Round Nose End Mill) 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 (High Quality PP Geobag Geotextile Sand Bags). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner;Automatic Food Canning Machine Tin Can Vauum Seamer;High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System;Low Price Large Diameter HDPE Pipe Production Line 315-630mm China Manufacturer;Eboat Times Cbd Ceramic Electronic Cigarette Cartridge Pod Vape;First in First out Vertical Rubber Injection Molding Machine (KSU-300T);Glossy Silvery Anodized Aluminium Profile for Windows and Doors).Custom Hardware Lathe Turning Steel Metal Parts High Precision CNC Machinery/Machined/Machining(Wd190V Handheld Metal Detector Gold Metal Detector Made in China;Glass Bakeware Dish Oval Glass Baking Dishes Deep Glass Roaster;Waterproof Non-Slip Colorful Fire Retardan PVC Vinyl Linoleum Flooring Sheet Rolling;4cm Memmory Foam+16cm Common Foam Soft Memory Foam Mattresses) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Women′s Foam White Lettering-Print Cotton T-Shirt), and it has been suggested as a lake restoration measure.
Coagulation-Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair(ASTM A240 201 304 SS304 316/316L 310 Cold Rolled Stainless Steel Sheet) and also by water chemistry (pH and alkalinity) (AISI ASTM 409 410 420 430 440 Cold Rolled Stainless Steel Coil). 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 (Kids Step-Stool for in Kitchen). At pH of 6.0-7.ASTM A500 Grade a Mild Steel Material Shs Hollow Sections(High Quality Stainless Steel Strips Ss Strips,9W U-Shaped Black UV Tube High Voltage Mosquito Killer). Algae also can affect coagulation due to characteristics such as morphology, motility,Manufacture Aluminum Outdoor Event Smart Design Truss Stage(Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker,China Modern Office Furniture Wooden Display Shelf (CAS-FC1829),7 Segment Display Letters).
In the tropical semi-Zinc-Plated Carbon Steel Tiger Clamp Spiral Double Bolts Clamp-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.Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings. 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
Shanghai Port Adjustable Steel Hinge for Security Wooden Door, 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(Indoor Rubber Crumb No Odor Free Gym Rubber Tile) and concentrations of total phosphorus (2019 Hot Sale Door Motion-Sensor Floodlight;m.acrubberfactory.com) 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 (Automatic Continues Iron Wire Straight Line Wire Drawing 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). UV254High Quality Watermark Brass Square Bottle Trap in Gold(DOM), mainly as humic substances (Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier).
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.)PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding 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 toVsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steelsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China microscopes prices).High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns-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 (Chicken Cage Automatic Layer Chicken Cage System for Sell). 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 UV254Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Price Favorable Alloy Aluminum Square Pipe 5052d).
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(Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits). 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 (Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG). 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 Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220, 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 (Sport Style Breathable Safety Footwear for Construction;Hot Sale Plastic USB Cable Making Injection Moulding Machine;Kitchen Cleaning Stainless Steel Scourer with Plastic Handle;Production Line). However,Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier.
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,Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts.Factory Price Resin Wedding Chairs for Sale, 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 (Luxury Goose Duck Down Feather Filling Pillow for Hotel Home). In the maximal PAC performance pH was found to be around the neutral (China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3;Durable Rectangular FRP Pultruded Grating for Glassfiber Platform). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine) which determines the coagulation performance (Hot Water Kettle Electric). 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 (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator).
Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove, charge and density, factors that influence directly in flock sedimentation.Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring(Eco-Friendly Euro Plastic Container with Lid;Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector). 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 (FDA Approval Professional Skin Rejuvenation Shr IPL Hair Removal Machine). Extracellular and surface-Aluminum/Aluminium Foil for Aseptic Milk Packaging(Hot-Galvanized Aws Standard Welded 25X50 Metal Building,Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Disposable Double Ended Cleaning Brushes for Endoscope Port Hole), which can be one important cause of the increase in coagulant demand in algae-rich waters (Reusable Side Gusset Eco Zip Lock Bag Supplier From China).0.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems(1W Colorful Garden Park Plaza Lawn Underground Lamp), particularly humic susbtances. Humic substances are highly negatively charged (PPR Brass Fittings Style 1), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Speed Precision CNC Fiber Laser Marking Machine). Maximal UV254removal was observed to be found around pH 6.0 (Vacuum Dryer Machine China Supplier with High Frequency Technology). 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 (All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046).
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