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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 (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine,Spray White Black Candle Holder Electroplate Rose Gold Candle Jar with Lid). As a result, several chemical methods have been applied to control P internal loading worldwide (700mm RP HP UHP High Quality Graphite Electrode;Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch;Furniture Laminate Sheet/HPL Panel/Building Material). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (7). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Alternator for Toyota 91, 92 Mr2, 100211-6110, 27060-74180, 2706074180, 1002116110, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Lds2000g Gasoline Power Cement Concrete Spray Pump Machines),Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory). 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 (Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale;Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant;Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1). However alum may result in high concentration of residual Al and is strongly affected by temperature (UV Digital Flatbed Printing Machine Seiko-1024) 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 (N95 Face Mask Respirator). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Mini Loader Radlader Mini Zl936 Wheel Loader;High Quality Compair Air Compressor Air Filter 50273;OEM Custom Precision CNC Machined Steel Parts;Professional Supplier of Hot Rolled Steel U Channel;Drip Irrigation Systems;Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop;Multi-Layer HDPE PE PPR Pipe Production Line).16mm Rotary Potentiometer with Switch for Audio Equipment(400W Vertical Axis Windmill Generator (200W-5kw);Auto Part PDC Parking Sensor for BMW 66209261595;Princess Inflatable Bouncy Jumping Castle Bouncer House with Slide (JC-02);Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush), and it has been suggested as a lake restoration measure.
Coagulation-Food Processing Industry Fruit Vegetable Drying Machine(Kfc Macdonald Food Grade Convenient Disposable PE Glove) and also by water chemistry (pH and alkalinity) (IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor). 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 (Live 500 600 1000 1200 Watt PA AMP Power Amplifier). At pH of 6.0-7.Hot Sale Bamboo Toothbrush in Flate Simple Design(Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting,OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose). Algae also can affect coagulation due to characteristics such as morphology, motility,L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906)(Custom Aluminum Steel CNC Machining Mechanical Turning Parts,Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands,1100 aluminum sheet 1100 h14 aluminum 1100 aluminum sheet suppliers 1100 aluminum plate).
In the tropical semi-Virtual Reality Egg Game Machine Amusement Riding Machine for Sale-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.7, 5kw Electric Conversion Kits for Light Car/Van/Truck. 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
Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller, 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(Fiber Laser Marking Machinery for Engraving Ribbon Metal Stainless Steel) and concentrations of total phosphorus (Factory Manufacturer CNC Dual Use Combined Metal Sheet Plate & Tube Pipe Fiber Laser Cutter;New Design Inflatable Soccer Darts) 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 (35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck). 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). UV254Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic(DOM), mainly as humic substances (China Factory Supply 25mm Blackout Pleated Honeycomb Blinds).
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.)Waste Pet Plastic Bottle Crushing Washing Recycling 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 toZ50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Intelligent Control Board Design PCB &PCBA Manufacture).12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery-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 (DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil). 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 UV254Outdoor LED Courtyard Solar Street Lights for Garden Path Road%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Diamond Candle Holderd).
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( Skateboard Shoes). 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 (Kids Electric Car with 12V Battery Remote Control). 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,Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate, 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 (Auto Parts for Plastic Products Injection Mould Mold Tooling;904L Stainless Steel Press Sheet with Hl Surface Finish; Cutting Bar;Automatic Wire Terminal Assembly Machine). However,Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250.
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,Manufacture Antique Hydraulic Electric Base Vintage Barber Chair.Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing, 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 (High and Low Temperature Humidity Chamber for Cycling Control). In the maximal PAC performance pH was found to be around the neutral (Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards;Precision Large 3 Axis Bench Metal Milling Machine Lm1450c). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2018 New Product Pendant Mounted 70W LED Garden Street Light) which determines the coagulation performance (Glass Bottle Nail Polish). 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 (Direct Steering Gear DC Motor with Low-Speed High Torque Spare Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ktz Series Best Slurry Pump Sewage Submersible Pump.
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