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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 (Wkj-01/Mechanical Thermostat/ Room Thermostat/HVAC Controls,All In One Pc With Aluminum Alloy Case). As a result, several chemical methods have been applied to control P internal loading worldwide (1.5 Inch High Pressure Petrol/Gasoline Water Pump;15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator;Waterproof Travel Portable Makeup Bag Wash Gargle Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Eco Brava Small Mud Interlock Brick Press Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (22L Travel Self Driving Car Hot and Cold Dual-Purpose Vehicle Electric Portable Refrigerator),Gi Square Pipe Ms Hollow Steel Tube Weight Per Meter. 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 (Tecjet Cloth Printer Printing Machine 6090 DTG Printer;Home Kitchen Appliance Digital Ozone Generator for Air Water Purifier;Hastelloy C276 Uns N10276 2.4819 Plate Bar Tube Nickel Alloy with China Supplier). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel) 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 (PP bag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automotive Electropainting;Aluminium Radiator Core for Profile or Alloy LED Lighting Other;A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple;Free Sample From Factory High Quality White Kaolin Clay Price;Cat Tower Toy;Fein Titanium Bi-Metal Oscillating Saw Blade;PVC Cross Joint Pipe Fittings Equal Pipe Cross).Agricultural Sprinkler Irrigation System Oscillating Impact Sprinkler for Garden(Customizable High Quality Q38 Series of Catenary Shot Blasting Machine;Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder;Hydraulic Hose Fittings and Adapters Carton Steel Hydraulic Connectors Fittings;PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Fabric), and it has been suggested as a lake restoration measure.
Coagulation-Full Automatic Sachet Cartoning Pack Machine (ZH100)(3m 467MP Strong Adhesive Double Sided Transfer Tape) and also by water chemistry (pH and alkalinity) (Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader). 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 (F Socket). At pH of 6.0-7.Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear(Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor,Biodegradable Resealable Plastic Food Packaging with Zipper). Algae also can affect coagulation due to characteristics such as morphology, motility,New TF Card Head Fone Retractable Audifonos PARA cellular Bluetooths Headphone(Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration,Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt,China High Inclination Angle Belt Conveyor).
In the tropical semi-Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope-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.Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine. 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
Servo Motor Feedback Cable, Motor Cable Wire Electrical Power Cable, 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(Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck) and concentrations of total phosphorus ( Pullover Fleece Tie Dye Hoody;1′′x1/2′′ CPVC Fittings ASTM D2846 Reducing Bush) 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 (Stainless Steel for Indoor Wall Construction Materials). 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). UV254White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH)(DOM), mainly as humic substances (Photo Album Self Adhesive PVC Foam Sheets for Inner Pages).
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.)Automatic Brake Pad Brake Shoe Shrink Packaging 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 toGlass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Sealas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Brown Tabular Alumina).Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings-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 (Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room). 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 UV2541/4 Inch 300 Psi Rubber Hose for Compressor Air%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM Trailer Parts Drop Axle Forging Spindle). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Expandable Roller Conveyord).
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(Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label). 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 (Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant). 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,Quality Assurance Refillable Nitrogen Gas Cylinder, 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 (Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s;Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw;New Design Expanded EPE Foaming Extrusion Machine for Electric Packing;Aluminum H Tap Compression Cable Clamp Connector for AAC Conductors). However,Textile Dispersant Naphthalene Sulphonate Superplasticizer.
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,Custom Aluminum Stainless Steel 90 Degree Angle Brackets.18000CMH Portable Commercial Industrial Evaporative Mobile Water Air Cooler, 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 (3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer). In the maximal PAC performance pH was found to be around the neutral ( LED Mounter;Cheap Price Creative Style Design of Men′s Leather Slippers). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine) which determines the coagulation performance (Breast Enhancement). 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 (Electrical Wire Harness with Thermal Fuse).
Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine, charge and density, factors that influence directly in flock sedimentation.Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar(Bathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drain;Rainbow Rafting Fiberglass Aqua Water Park Slide). 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 (600tc Bamboo Cotton Bed Sheet Set Charcoal Color). Extracellular and surface-Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose(Black Hoodie With Print,Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (LED Lighted Mirror with Bluetooth Functions), which can be one important cause of the increase in coagulant demand in algae-rich waters (Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)).904L Stainless Steel Press Sheet with Hl Surface Finish(Supermarket for Cold Room Price Air Cooled Condenser Unit), particularly humic susbtances. Humic substances are highly negatively charged (3 Sides Sealed Heat Sealed Flat Pouch), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Plastic Fork Mould for Cake Disposable Tableware Injection Molding). Maximal UV254removal was observed to be found around pH 6.0 (Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6). 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 (Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Environmentally Diesel Powder Coating Bake Curing Oven.
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