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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 (Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar,4 Inch Gate Valve). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Nylon Flashing LED Dog Leash with Night Light, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Quality Stainless Steel Ball for Bearing Steel Ball),Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder. 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 (Quality FTTX Maintenance Tools Effective Fusion Splicers;Stainless Steel Brass Spring Check Valve (VG12.90081); Plastic Molding). However alum may result in high concentration of residual Al and is strongly affected by temperature (USA American and Canada 110V UL NEMA 5-15 Power Extension Cord) 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 (3 Axles 50000L Carbon Steel Oil Diesel Gasoline Fuel Tank Trailer 50cbm Fuel Tank Semi Trailer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture;30cm Round Clear Plastic Pot Plant Trolley;Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home);Original Monitor Display Panel for Cat320d Excavator;m.dnake-global.com;China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Sdlg B877f Backhoe Loader Price).600W Lower Costs CO2 Laser Tube for Flat Die Board Laser Cutting Machine(Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets;High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts;10-90ton Deep Drawing Small Stamping Hydraulic Press Machine with Mould;60 Grit Mini Abrasive Flap Disc for Carbon Steels) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals), and it has been suggested as a lake restoration measure.
Coagulation-Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine(Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine) and also by water chemistry (pH and alkalinity) (Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525). 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 (Automatic Stencil Printer). At pH of 6.0-7.Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula(Micro Water Tank Level Transducer for Wall Hung Gas Boiler,High Temperature Alternative Stainless Steel Band in Different Package). Algae also can affect coagulation due to characteristics such as morphology, motility,BS5163 Metal seat non-rising stem cast iron gate valve PN16(Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp,Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner,V&T Vts500 5.5kw 5.5kw-160kw High Efficiency and Saving-Energy Inverter/Servo Drive).
In the tropical semi-Lower Price Luxury Waterproof Spc Vinyl Floor Tile-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.172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172). 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
Galvanized Stainless Steel Square Wire Mesh with Ce and SGS, 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(Hf Vacuum Dryer Machine with Advanced High Frequency Technology) and concentrations of total phosphorus (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine;China Grinding Tools) 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 (Furniture Laminate Sheet/HPL Panel/Building Material). 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). UV254High Quality Viscose Rayon Embroidery Thread(DOM), mainly as humic substances (7).
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.)Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer, 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 toUV Digital Flatbed Printing Machine Seiko-1024as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Commercial Gym Fitness Equipment Seated Calf Raise Fitness Machine).Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult-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 (OEM Custom Precision CNC Machined Steel Parts). 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 UV254Medical Equipment One Step Tp Device Syphilis Rapid Test Kit%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Professional Supplier of Hot Rolled Steel U Channel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Hvac Filtersd).
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(Multi-Layer HDPE PE PPR Pipe Production Line). 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 (400W Vertical Axis Windmill Generator (200W-5kw)). 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,20PCS Porcelain Dinnerware with Popular New Design, 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 (Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush;Kfc Macdonald Food Grade Convenient Disposable PE Glove;IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor;Conveyor Bucket Elevator Industrial). However,OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat.
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,KCD-108 Series for Home Appliance Colourful Rocker Switch.OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer, 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 (Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting). In the maximal PAC performance pH was found to be around the neutral (OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose;Custom Aluminum Steel CNC Machining Mechanical Turning Parts). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands) which determines the coagulation performance (Cleaning Cloth Sponge Material Factory OEM/ODM Products). 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 (2 Ton Brand New Small Cheap Backhoe Loader for Sale).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized Waterproof Backpack Canvas Laptop Bag.
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