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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 (Automotive Aluminum Engine Parts Low Pressure Casting,Camera Photo Studio Light). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C; Aluminum Hurricane Rolling Shutter;Waterproof Carbon Fiber Hard EVA Case for 3D VR). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manual Brass Button Time Delay Auto Stop Urinal Flush Valve (C-16), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (4 Channels Mini Size 1080p Hard Drive And Sd Card Vehicle Mobile Dvr With Anti-Shock Gps 3g 4g Wifi Optional),Competitive Price Corrugated Tubing with Braid Layer. 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 (Galvanized Steel Spiral Duct for Ventilation Ducting;Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074);Four Wheels Portable Electric Mobility Scooter with Lithium Battery). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine) 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 (All Terrain Pallet Stacker). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies;Safety Disposable Shoe Cover for Lab Visitor;Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#);High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754);Anti Counterfeit Label;New Items Personalized Teething Toy Baby Pacifier with Panda Shape;Tb10-30kVA Low Frequency Online UPS High Efficiency UPS with Snmp).5/8 Inch Stainless Steel Banding in Plastic Tote(Australia Rcm Testing and Certification Service for Power Adapter;1/4 Inch 300 Psi Rubber Hose for Compressor Air;316L Stainless Steel CNC Diamond Ear Stud with Roman Letters;Receipt Book/Invoice Book/Business Form Book) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Colorful Fashion Women Sneaker Walking Weave Shoes(Precision Machining Components for Hydraulic Cylinder Producing) and also by water chemistry (pH and alkalinity) (Professional Salon Use Plastic Hair Coloring Comb). 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 (China All In One 3d Printer Cnc Laser). At pH of 6.0-7.Industrial Small Air Centrifugal Blower Ventilator Fan and Exhaust Fan(OEM Precision Steel Milling Machining Auto Parts,Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic Alcohol Swabs Wipes Pads Tissue Packaging Machine Price(Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting,Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar,Home Use High Power Wrinkle Removal Beauty Machine).
In the tropical semi-Q235 Galvanized Steel Hoop Iron Strap for Packaged Timber House-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.12L Ice Chest Ice Bucket Plastic Cooler Box. 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
Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock, 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(Lifting and Hoisting Industrial Manual Chain Lever Block Vt) and concentrations of total phosphorus (Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set;Bottom Price Extrusion Pvc Profile) 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 ( Plastic Molding). 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). UV254P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum(DOM), mainly as humic substances (USA American and Canada 110V UL NEMA 5-15 Power Extension Cord).
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.)20FT Double Axle Skeletal Port Trailer Container Semi Trailer Chassis, 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 toOriginal Monitor Display Panel for Cat320d Excavatoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Anti-Oxidation FRP Roofing Sheet for Textile Industry).Floor Mounted Glass U Clamp Channel for Glass Balustrade-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 (Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets). 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 UV254Contec Cms-Vesd Digital Multi-Functional Visual Stethoscope with SpO2/Estetoscopio%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Custom Sized Vegetable Capsulesd).
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(High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals). 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 (Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine). 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,1.5 Inch High Pressure Petrol/Gasoline Water Pump, 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 (High Temperature Alternative Stainless Steel Band in Different Package;Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp;Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner;m.wh-machine.com). However,China Stainless Steel Clamp Sanitary Ball Check Butterfly Valve.
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,Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger.Small Mini Homemade Grain Corn Maize Powder Feed Grinding Mill, 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 (New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges). In the maximal PAC performance pH was found to be around the neutral (Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Hf Vacuum Dryer Machine with Advanced High Frequency Technology). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine) which determines the coagulation performance (Pet Animal Food Mill Extruder Machine/Floating Fish Feed Pelletizer Granulator). 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 (700mm RP HP UHP High Quality Graphite Electrode).
Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle, charge and density, factors that influence directly in flock sedimentation.Dog Cat Car Products Travel Accessories Seat Pet Carrier Bag(Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch;Furniture Laminate Sheet/HPL Panel/Building Material). 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 (7). Extracellular and surface-High Tensile Forged Chain with Conveyor for Conveying System(PS Foam Food Container/Lunch Box/Tray/Bowl/Plate Making Machine,Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant), which can be one important cause of the increase in coagulant demand in algae-rich waters (Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1).Dny Automatic Stainless Steel 304 Belt Filter Press(UV Digital Flatbed Printing Machine Seiko-1024), particularly humic susbtances. Humic substances are highly negatively charged (Wood Chipper Making Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New Mini Loader Radlader Mini Zl936 Wheel Loader). Maximal UV254removal was observed to be found around pH 6.0 (High Quality Compair Air Compressor Air Filter 50273). 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 (OEM Custom Precision CNC Machined Steel Parts).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H).
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