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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 (Color Bristol Board Paper Manila Paper Leather Grain Embossed Paper,Sign Bending Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (2019 Fashion Women Hot Red All The Rage Skater Party Cocktail Dress;Intelligent Robotic Soldering Machine (Computer Based) / Soldering Robot;Indoor High Definition TV Screen P1.667/P1.875 /P1.923 LED Display Wall). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (11kv-33kv Polymer Dropout D Fuse Cutout/Expulsion Fuse with Silicone Housing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Flexibel Hose Assembly Machine Factory OEM/ODM Products),Double Head Round Bar Chamfering and Deburring Machine. 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 (Police Disposable Nylon66 Handcuff with Two Loop;Construction Machine Cement Concrete Mixing Mixer Batching Plant Hzs75;Stainless Steel Union Type pneumatic Butterfly Valve with Control Head). However alum may result in high concentration of residual Al and is strongly affected by temperature (100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll) 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 (Anchor Chain Accessory). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Solar Garden Peacock Stake with Solar Light for outdoor Decoration;Eco Friendly Kraft Biodegradable 5ml Bamboo Lip Balm Tubes Lipstick Tube;Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice;New Bioplasm Nls Quantum Full Body Health Scanner with Therapy Function;Smoking Device For Heet;Jm-613 Made in China High Quality Conference Microphone Gooseneck Embedded Microphone;Modern Ladies Clothes Shop Design for Clothing Store Display).Scaffolding Deck Galvanized Steel Walking Board Metal Plank for Scaffold 250*40*1.2*4000mm(Stainless Steel Water Filter Housing RO Systems; Mechanical Infant Scale;All Red Led Grow Light;Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose), and it has been suggested as a lake restoration measure.
Coagulation-Pen-Type Food Thermometer, Digital Thermometer E278(Video Endoscope with 5.5 Wireless) and also by water chemistry (pH and alkalinity) (Fresh Mung Bean Filling Stand-up Pouch Packing Machine). 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 (2 Colors Lanyard Ribbons Automatic Screen Printing Machine). At pH of 6.0-7.Sports Meeting Concert Cheering Props Football Horn(Factory Flint Lighter Disposable Cheap Chinese Lighter Plastic Lighter,Portable Ultrasound Machine Vacuum Therapy Weight Loss Physiotherapy Equipment). Algae also can affect coagulation due to characteristics such as morphology, motility,China Tamping Rammer with Hondagx160 Supplier(50*50*5mm Galvanized Angle Steel Bead Angle Iron with SGS Certificate China Supplier,304 316L 321 904L 2205 1.4401 2507 Hot Rolled Stainless Steel Coil,Medical Oxygen Plant).
In the tropical semi-Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier-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.Cee/IEC 32A 5p 400V 3 Phase European Standard 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
Induction Heater Electric High Temperature Furnace for Casting, 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(Wet Dry Diamond Polishing Pad Concrete Polishing Resin Pads) and concentrations of total phosphorus ( stainless steel 316/304;Hongjun 6 Axis 20kgs Automatic CNC Industrial Manipulator) 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 (OEM Basketball Sport Longer Elastic Leg Guard Shin Guard). 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). UV254300W 600W Solar Submersible Deep Well Pumps, Solar Water Pump for Garden Irrigation (SC Series)(DOM), mainly as humic substances (High Purity Granulated Sodium Chloride for Deicing Road Salt).
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.)Sbm Best Sales Vertical Milling Machine, Limestone Roller Mill, 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 toC37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulbas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Perfume Bottle 100 Ml).Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk-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 (925 Fashion Silver Heart Earrings Stud Simple for Sale). 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 UV254Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fiberglass Reinforced Plastic Composite FRP Grating Pultruded). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Semi-Automatic Fired Earth Clay Soil Clay Brick Making Machine/Block Machined).
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(ASTM E1474 Cone Calorimeter Heat Release Rate Flammability Testing Equipment). 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 (Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles). 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,Used Fashion Summer Children′s Dress Unsorted, 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 Efficiency 5 in 1 Mug Heat Press Machine;3core 95mm 185mm XLPE Cable Armored Electric Cable; /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR;Electric Tower Crane Arm Single-Arm Endoscopic Pendant Esp-220/380e). However,Custom Aluminum Housing with Anodizing Color, Aluminum Enclosure for LED.
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,Bolts and Nuts Set Brass Fasteners Double Hex Bolt.Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment, 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 (Exquisite Workmanship Rubber Shoe Vulcanizing Autoclave with Electric Heating). In the maximal PAC performance pH was found to be around the neutral (RF Wrinkle Removal IPL Hair Removal Skin Rejuvenation Beauty Salon Equipment with Filter;Retract Drill Mining Rock Thread Button Bit). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink) which determines the coagulation performance (Black Mesh Sport Bra Running Top Sexy Yoga Bra Top Sportswear Workout Clothing). 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 (Stainless Steel Waterproof Anti-Explosion Ik10 IP65 LED Linear Tube Light).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fashion Double Striped Non-Slip Entrance Mat.
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