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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 (High Quality Stainless Steel Strips Ss Strips,Black Desk Lamp Shade Wholesaler Quotes & PriceList). As a result, several chemical methods have been applied to control P internal loading worldwide (9W U-Shaped Black UV Tube High Voltage Mosquito Killer;Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker;China Modern Office Furniture Wooden Display Shelf (CAS-FC1829)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Furnitures). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Laser Cutting Metal Ceiling Design),HPMC for White Cement Admixtures Putty Powder Additives. 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 (China Factory Anesthesia Apparatus Circuit Board PCBA Manufacturer One-Stop Assembly;Indoor Rubber Crumb No Odor Free Gym Rubber Tile;2019 Hot Sale Door Motion-Sensor Floodlight). However alum may result in high concentration of residual Al and is strongly affected by temperature (Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66)) 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 Wc-08 Wood Chipper with GS/Ce Approval). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ce High Quality Stylish SMD LED Flood Light 10W 20W 30W 50W 100W 150W 200W;Automatic Continues Iron Wire Straight Line Wire Drawing Machine;Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier;Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap;Singel Handle Stainless Steel Kitchen Sink Faucet Pipe;Portable Marking Equipment System Laser Wire Marking Machine Price;High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress).Garden Stone Table &Chair, Granite Outdoor Table(Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels;5kg Pleasant Scent Brilliant Fasclean Extra Top Laundry Detergent;Factory Professional Embossed Frosted PVC Sheet for Book Cover;1kg Oxygen Source Ozone Generator for Waste Water Treatment) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Chicken Cage Automatic Layer Chicken Cage System for Sell), and it has been suggested as a lake restoration measure.
Coagulation-Hot and Cold Temperature Thermal Shock Testing Equipment(Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6) and also by water chemistry (pH and alkalinity) (Manufacture Antique Hydraulic Electric Base Vintage Barber Chair). 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 (405/30/50sg Hot Dipped Galvanizing Steel Grating). At pH of 6.0-7.Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps(Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits,Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG). Algae also can affect coagulation due to characteristics such as morphology, motility,Water Centrifugal Pump for Swimming Pool Water Transfering(Back Bar Beer Cooler,Customized High Precision CNC Machining 7075 Aviation Aluminum Metal Parts,Diameter 0.1-10mm Fe-Cr-Al Alloy 0cr21al6 Wire for Heating Element).
In the tropical semi-18mm Znse Focal Lens 10600nm CO2 Laser Engraver Cutter Focus 1.522.5-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.3D Skin Test Device for Skin Loosen/Pigmentation/Pore/Wrinkle/Moisture Content. 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
Cryotherapy Fat Removal Coolsculpting System Body Contouring 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(Kitchen Cleaning Stainless Steel Scourer with Plastic Handle) and concentrations of total phosphorus (Luxury Goose Duck Down Feather Filling Pillow for Hotel Home;Angle Stop Valve) 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 (2000W Stainless Steel CNC Fiber Metal Laser Cutting 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). UV254Customized Logo Personalized PVC Cup Coaster with Gift Box(DOM), mainly as humic substances (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator).
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.)Portable Far Infrared Sauna Dome with Tourmaline Stone, 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 toSoft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Empty Car Perfume Bottle).Accessories of Anchoring Round 2 Holes Anchorage Block with Wedges-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 (1W Colorful Garden Park Plaza Lawn Underground Lamp). 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 UV25420 Inch Male Thread European Style Blue Filter Cartridge Housing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Speed Precision CNC Fiber Laser Marking Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel Grinderd).
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(All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator). 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 (Auto Electrical Heater Blower Motor for Benz 2208203142). 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,Mini Building up Block Pen Highlighter Marker Pen Writing Drawing Stationery, 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 (Factory Cafe Furniture Rectangular Dining Table;2019 China Professional PE/PP Knotless Net Extrusion Line Machine;Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair;24 Hours Mechanical Timer). However,Hot Sell Peptides Follistatin 315 Price--Factory Direct Supply 99% Purity.
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,Armor Thermocouples / Thermal Resistance Temperature Sensor.High Quality Sand Paper for Sand Machine Brush (YY-170), 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 (Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe). In the maximal PAC performance pH was found to be around the neutral (BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle;Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock) which determines the coagulation performance (PE HDPE Silicon Core Cable Duct Plastic Pipe Extruder Machinery). 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 (Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon).
High Tolerance Stainless Steel Stamping Parts Enclosure,, charge and density, factors that influence directly in flock sedimentation.Class 1 Foam Rubber Insulation Pipe for Air Conditioner(for Bahrain Market Hot Cafe Vending Machine F303V;China Supplier PPGI Coils for Construction Materials). 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 (HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck). Extracellular and surface-Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly(m.nsen-valve.com,High Accurate LCD Digital Medical Flexible Oral Thermometer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV), which can be one important cause of the increase in coagulant demand in algae-rich waters (Panasonic Ai Spare Parts X004075 with Large Stock).Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966(Ceramic Components Applied in Machinery Industry), particularly humic susbtances. Humic substances are highly negatively charged (www.excaliburgenerator.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (EPS100 Nts100 Xns100 Common Rail Injector Test Bench). Maximal UV254removal was observed to be found around pH 6.0 (BS5163 Metal seat non-rising stem cast iron gate valve PN16). 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 (12mm Thickness Square Corrugated Cake Board).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003).
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