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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 (Australia Rcm Testing and Certification Service for Power Adapter,Stainless Steel Hygienic Welding-Welding Butterfly Valves). As a result, several chemical methods have been applied to control P internal loading worldwide (1/4 Inch 300 Psi Rubber Hose for Compressor Air;Receipt Book/Invoice Book/Business Form Book;10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Precision Machining Components for Hydraulic Cylinder Producing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,22mm 2no2nc Metal on off Start Button Power Push Button Switch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Customized Progressive Mold Stainless Steel Sheet Metal Stamping),Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack. 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 (Professional Salon Use Plastic Hair Coloring Comb;OEM Precision Steel Milling Machining Auto Parts;Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting) 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 (Large Plastic Wrap For Moving). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar;Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration;Kw-700 Industrial Commerical Driving Type Floor Scrubber Price;Lifting and Hoisting Industrial Manual Chain Lever Block Vt;High Accuracy Electrophoresis Power Supply with Factory Price;Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set;Quality FTTX Maintenance Tools Effective Fusion Splicers).Beauty Equipment Face Lifting Hifu Equipment(Stainless Steel Brass Spring Check Valve (VG12.90081); Plastic Molding;LED Letter Sign Fancy Light for Wedding/Party/Christmas Decoration;USA American and Canada 110V UL NEMA 5-15 Power Extension Cord) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture), and it has been suggested as a lake restoration measure.
Coagulation-Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008)(30cm Round Clear Plastic Pot Plant Trolley) and also by water chemistry (pH and alkalinity) (Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home)). 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 (Chinese Lift). At pH of 6.0-7.LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse(Original Monitor Display Panel for Cat320d Excavator,China Manufacrure Mobile Asphalt Batch Mix Plant for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU(Sdlg B877f Backhoe Loader Price,Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets,Light Masts).
In the tropical semi-Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag-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.Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug. 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
Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel, 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(High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals) and concentrations of total phosphorus (Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine;China rubber mud suction hose) 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 (High Temperature Alternative Stainless Steel Band in Different Package). 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). UV254Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer(DOM), mainly as humic substances (Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp).
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.)Manufacturer Woven Patches and Customized Woven Badge, 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 toHf Vacuum Dryer Machine with Advanced High Frequency Technologyas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(6630 Dmd Factory OEM/ODM Product).Portable for Mobile 120W 24V Automatic Car Key Cutting Machine-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 (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch). 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 UV254Fashionable New Products Twin Screw Extruder for Pet Recycling%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Furniture Laminate Sheet/HPL Panel/Building Material). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Single Head Electric Shaverd).
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(Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale). 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 (Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant). 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,V4 Type Sintered Porous Filter with Female Thread, 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 (New Mini Loader Radlader Mini Zl936 Wheel Loader;High Quality Compair Air Compressor Air Filter 50273;OEM Custom Precision CNC Machined Steel Parts;China Double Glazed Door). However,Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine.
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,Steel Drilling Water Well Filter / Bridge Slot Screen Pipe.Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System, 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 (Professional Supplier of Hot Rolled Steel U Channel). In the maximal PAC performance pH was found to be around the neutral (Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop;Multi-Layer HDPE PE PPR Pipe Production Line). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (400W Vertical Axis Windmill Generator (200W-5kw)) which determines the coagulation performance (Astar Catering Equipment Counter Top Luxury Gas 2-Tank Deep Fryers). 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 (Auto Part PDC Parking Sensor for BMW 66209261595).
Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer, charge and density, factors that influence directly in flock sedimentation.Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange(Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank;Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush). 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 (Kfc Macdonald Food Grade Convenient Disposable PE Glove). Extracellular and surface-Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set(Cast Iron Electric Fire Suite,IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting), which can be one important cause of the increase in coagulant demand in algae-rich waters (OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose).Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel(Custom Aluminum Steel CNC Machining Mechanical Turning Parts), particularly humic susbtances. Humic substances are highly negatively charged (Cylindrical Filter Element Supplier & Factory), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands). Maximal UV254removal was observed to be found around pH 6.0 (2 Ton Brand New Small Cheap Backhoe Loader 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 (Galvanized Wire Fence Building Barbed Wire Fence Pictures).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger.
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