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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 (Magic Mirror Facial Skin Analyzer / 3D Face Camera,High Quality 33kv Outdoor Metal Oxide Lightning Arrester Distribution Type). As a result, several chemical methods have been applied to control P internal loading worldwide (Cement Grout Pump Grouting Machine Price Concrete Grouting Machines;Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery;Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Brass Component Auto Parts Medical Equipment CNC Machining). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Biscuit Oven Belt Conveyor),NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor. 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 (Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear;Zxx-C2518 Glass Shower Door Cut Outs Making Machine Glass Work Center;Outdoor Decoration Small Music Dancing Garden Water Feature Fountain). However alum may result in high concentration of residual Al and is strongly affected by temperature (Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope) 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 (Direct Cooling Ice Block Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Economical Wall Decoration PVC 3D Brick Wallpaper Designs;1.0mm Pitch Right Angle Wire to Board Connector FFC/FPC Connector;DFAC High Altitude Operation Platform Truck 10m for Sale;Y Series 315 Case High Power 75kw 90kw 110kw 132kw 6-Pole Three-Phase AC Motor;130lm/W Urg;LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens;Swivel Hook Auto Engine Valve Spring Motor Spring).Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles( Security Protected Razor Barbed Wire/Blade Barbed Wire;Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles;www.aviationaluminum.com;Galvanized Pullet Chicken Cage Baby Chicken Cages) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light), and it has been suggested as a lake restoration measure.
Coagulation-19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment(CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories) and also by water chemistry (pH and alkalinity) (Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment). 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 (Cold Drawn DIN17175 St35.8 Carbon Steel Seamless Tube). At pH of 6.0-7.Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw(Sheet Metal Stamping Galvanized Steel Panel and Frame,Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men(IP65 8W Outdoor Integrated LED Street Light Solar Lamps,CNC Turning Stainless Steel Part with Precision Tolerance,Auto Car Part Packing Sensor).
In the tropical semi-Concrete Road Cutting Machine, Road Cutter, Road Saw Machine-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.Soyo Energy Aluminum Alloy Solar Ground Mounting System. 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
Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561), 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(Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven) and concentrations of total phosphorus (THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC;Auto Air Fuel Pressure Regulator for Renault 928400627) 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 (2019 New Crop Blanched Peanut Kernels (long shape) From China). 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). UV254New Mini Loader Radlader Mini Zl936 Wheel Loader(DOM), mainly as humic substances (Absorbent PP Mat Hardwearing Doormat with Round Shape).
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.)Fein Titanium Bi-Metal Oscillating Saw Blade, 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 toAluminium/Brass/Stainless Steel Cam Lock Quick Couplingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Boys Short Swimwear).Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863-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 (Electric Rail Transport Wagon Warehouse Transfer Vehicle). 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 UV254FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (3kg Enzyme Laundry Washing Powder / Detergent Powderd).
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(Low MOQ Perfect Binding Soft Cover Book Printing High Quality). 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 (24V/48V 40A/80A MPPT Solar Charge Controller for Solar Power System). 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,Handrail Fitting / Stainless Steel Round & Square Tube Connector, 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 (Amino Acid Magnesium Chelate for Organic Fertilizer;Nc Hydraulic Bending Tube Metal Pipe Bending Processing;Best Quality Plastic Wall Plug Expansion Anchor;Antique Iron Fence). However,Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car.
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,BRT Gasoline Log Splitter 22 Ton Firewood Processor.Android Data Cable Mobile Phone USB Cable Mobile Phone Cables, 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 (700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346)). In the maximal PAC performance pH was found to be around the neutral (Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce;Outdoor Waterproof IP68 LED Structure 3D Arch Street Christmas Decoration Ball Motif Lights). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Home Used Portable Fencing Aluminium Swimming Pool Safety Fence) which determines the coagulation performance (Sorbitol 70% Powder). 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 (40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine).
Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press, charge and density, factors that influence directly in flock sedimentation.Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook(2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC);Promotion LCM Custom LCD Display Stn FSTN Cog LCD Positive Graphic LCD Display Module for). 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 (94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent). Extracellular and surface-Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter(40w Vintage Edison Bulb,Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (72tpd RO Water Treatment Sea Water Desalination Equipment), which can be one important cause of the increase in coagulant demand in algae-rich waters (New Design Pet Product).Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508(22mm 2no2nc Metal on off Start Button Power Push Button Switch), particularly humic susbtances. Humic substances are highly negatively charged (Angle Steel Bar), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India). Maximal UV254removal was observed to be found around pH 6.0 (Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale). 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 (Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Transparent High Quality Building Glass Curtain Wall From China Suppliers.
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