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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 (Ce Approved Cheap Medical Disposable Electrical Infusion Pump,Avss Low Voltage Flexible Automotive Wire Jaso Standard for Car Automobile PVC Insulation Cabl). As a result, several chemical methods have been applied to control P internal loading worldwide ( Sany Pump Truck;Textile Dispersant Naphthalene Sulphonate Superplasticizer;2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Outdoor Event Pop up Canopy Easy up Advertising Tent, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ice Silk Underwear),Customized Various Aluminum Hardware Fastening/Real Accessories. 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 (Stainless Steel Housing Washable Ss Filter Cartridge Automatic Backwash Filter;Customized Small Wind Turbine Generator Permanent Magnet;Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid) 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 (Soft King Queen Full Twin Us Size Solid Color Bed Sheet Tencel Bedding Sets Duvet Cover Set). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Manhole Cover Stainless Manway Tank Hatch Cover;Compostable White Take Away Disposable Paper Lunch Box;Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats;Factory Direct Seal Y14f General Power Relay 5 Pins;Carbon Steel CNC Machining Sliding Worm Shaft Precision CNC Milling Machining Spare Parts;Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror;Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks).Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil(Flexible Cloth Backdrop P18 3X6m LED Video Curtain;1oz Square Glass Storage Mason Jar with Cork Lid;Wall Mount Antennas;2016 500W Razor Crazy Electric Drift Trike for Adult) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Low Cost Commercial Plastic Film Greenhouse for Sale), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Humidity Control Chamber Artificial Climate Chamber(Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring) and also by water chemistry (pH and alkalinity) (Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose). 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 (Baby Dinosaur Hand Puppet). At pH of 6.0-7.CNC Precison Red Painting Titanium Alloy Machinery Parts(11mm Neck Crimp Cap Vials with Patch,608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing). Algae also can affect coagulation due to characteristics such as morphology, motility,I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds(Slotted Hex Head Self Drilling Screw with EPDM Washer,Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration,Milling Fixture).
In the tropical semi-New Design Contact Infrared Baby Ear Thermometer Jl0158-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.Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag. 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
OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector, 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(20 Inch Male Thread European Style Blue Filter Cartridge Housing) and concentrations of total phosphorus (M8*30 Cucrzr Contact Tip Welding Accessories for Welding Torch;Rubber Compression Press Rubber Mat Molding Press Rubber Vulcanizing Press) 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 (IPS No. 6 Dtp Automatic Smart Wrist Watch 2019). 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). UV254Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine(DOM), mainly as humic substances (Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring).
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.)Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM, 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 toGood Quality UV Drying Heater for Silk Screen Printingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot Rolled Low Carbon Straight Seam Pipe Used for Structure).Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects-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 (Dia120mm*120mm Casting Swivel Anchor Nut for Formwork and Scaffolding Accessories). 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 UV254Permanent Magnetic Grid for Europe Market%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Large Size Double Flange Rubber Lined Butterfly Valve with Worm Gear Operated). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bouillon Cube 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(5.5kw Three Phase AC Asynchronous Induction Electric Motor Price). 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 ( Drawing Book for Students). 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,New Fitness Commercial Exercise Spinning Bike, 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 (Forged Lifting Load Hanger Clevis Sling Hoist Hook;Food Machine/Chd330 Compact Carrot Cutter Cutting Machine;Hot Sale Farm Implement 1bzd Series Tractor Mounted Hydraulic Opposed Hydraulic Disc Harrow;Love Paper Bag). However,Ce Approved Disposable Paper Mask, 2 Ply Beauty Face Mask.
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,Vertical Gas Boiler for Water Heating in Biogas Plant.CO2 Laser Engraving Cutting Machine for Acrylic, 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 (Industrial 128X64 Cog LCD 28 Pin TFT White LED Transflective MP4 Mono LCD Display Screen Module). In the maximal PAC performance pH was found to be around the neutral (Customized China Fabrication Companies Workshop Warehouse High-Strength Steel Structure;Galvanized Cast Iron Floor Sow Farrowing Crates with Piglets Nursery Crates). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Carbon Steel Zinc Countersunk/ Flat Head Self Tapping Screw) which determines the coagulation performance (15.6 40pins Edp 4K LCD Panel with High Resolution: 3840X2160 Lq156D1jx01b for 3D Printer). 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 (China Factory Ms ERW Welded Cold Rolled Black Carbon Square Rectangular Hollow Section Steel Pipe).
Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts, charge and density, factors that influence directly in flock sedimentation.VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A)(23.6 Inch Aio / Quad-Core All-in-One PC with Touch Screen; Square Plate). 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 ( Muffin Pastry Box). Extracellular and surface-304 316 1.4301 1.4404 Stainless Steel Angle with Sharp Edge(m.yikoocam.com,Silver Reflective One Way Vision Film as Mirror Performance (SF101)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (13.56MHz Logo Printing Mini NFC Epoxy Card for Access System), which can be one important cause of the increase in coagulant demand in algae-rich waters (PPGI/PPGL Prepainting Galvanized Steel with Ral Color).up-Down Table 1390 100W CO2 CNC Laser Cutter Machines(Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab), particularly humic susbtances. Humic substances are highly negatively charged (Plastic PVC Rubber Fitting Injection Moulding Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Highway Outdoor Road Integrated Solar LED Street Light Price List). Maximal UV254removal was observed to be found around pH 6.0 (Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid). 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 (Light Weight Concrete AAC Brick/Block Making Machine for Wall Material).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Glass Bakeware Dish Oval Glass Baking Dishes Deep Glass Roaster.
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