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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 (Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration,Mini Tws Wireless Earbuds). As a result, several chemical methods have been applied to control P internal loading worldwide (Sinbeda LCD Display for Sony Xperia Z1 Touch Screen;CNC Milling Service /CNC Aluminum Turning /CNC Machining Part;Color Bristol Board Paper Manila Paper Leather Grain Embossed Paper). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2019 Fashion Women Hot Red All The Rage Skater Party Cocktail Dress). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Rcm Certification for Scanning Electronic Input Pen, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Popular Summar Party Folding Injection 900W Foam spray Machine for Foam Party),1/2, 1/4, 1 High Alumina Ceramic Ball with High Quality. 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 (Intelligent Robotic Soldering Machine (Computer Based) / Soldering Robot;Indoor High Definition TV Screen P1.667/P1.875 /P1.923 LED Display Wall;11kv-33kv Polymer Dropout D Fuse Cutout/Expulsion Fuse with Silicone Housing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Police Disposable Nylon66 Handcuff with Two Loop) 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 (Wooden Kids Children Study Table and Chair Set Preschool Table and Chair). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Construction Machine Cement Concrete Mixing Mixer Batching Plant Hzs75;Stainless Steel Union Type pneumatic Butterfly Valve with Control Head;100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll;Solar Garden Peacock Stake with Solar Light for outdoor Decoration;Jewellery Marking Machine For Bangle;Eco Friendly Kraft Biodegradable 5ml Bamboo Lip Balm Tubes Lipstick Tube;Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice).Surface Paiting Line UV PU Water Base Spraying Robot Arm(New Bioplasm Nls Quantum Full Body Health Scanner with Therapy Function;Jm-613 Made in China High Quality Conference Microphone Gooseneck Embedded Microphone;Quickly Clumping Tofu Cat Litter;Modern Ladies Clothes Shop Design for Clothing Store Display) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Water Filter Housing RO Systems), and it has been suggested as a lake restoration measure.
Coagulation-Fashion Logo Soft LED Neon Sign for Home and Bar Signage( Mechanical Infant Scale) and also by water chemistry (pH and alkalinity) (Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder). 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 (Bajo Acústico). At pH of 6.0-7.10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine(China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose,Video Endoscope with 5.5 Wireless). Algae also can affect coagulation due to characteristics such as morphology, motility,LG Mj1 3500mAh 3.7V Rechargeable 18650 Lithium Battery for Power Bank(Fresh Mung Bean Filling Stand-up Pouch Packing Machine,Factory Flint Lighter Disposable Cheap Chinese Lighter Plastic Lighter,Water Level Detection Pressure Transducer).
In the tropical semi-Healong Fashion Sportswear Latest Design Blank Gym Sweatshirts Custom Cotton Hoody Sweatshirts-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.Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock. 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
2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card, 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(304 316L 321 904L 2205 1.4401 2507 Hot Rolled Stainless Steel Coil) and concentrations of total phosphorus ( Air Conditioner;Double Nylon Camping Hammock) 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 ( stainless steel 316/304). 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). UV254Flash Freezing Equipment Stainless Steel Freezer Blast Freezer Chiller Cabinet(DOM), mainly as humic substances (High Precision CNC Turning Milling with Good Price).
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.)9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting, 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 toGalvanized Wire Rope Sling with Eyes at Both Endsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Shanghai Mold Manufacturer Making Cheap Precision Silicone Plastics Injection Mould).Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner-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 (C37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulb). 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 UV254New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fashion Sports Woven Wristband with Print Logo). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (3 Phase Surge Protection Deviced).
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(925 Fashion Silver Heart Earrings Stud Simple 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 (Fiberglass Reinforced Plastic Composite FRP Grating Pultruded). 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,New Material of Coated and Veneered Wooden Grain Paper, 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 (Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles;Construction Structure Steel Shot Blasting Cleaning Machine;Electronic Lab Aging Test Chamber UV Light Tester with 340 a B Lamp;UL Ce 1210 3528 High Density 120 LEDs/M IP66 Flexible Strip LED). However,All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable.
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,Wholesale Foldable Desk Silicon Mobile Phone Stand.300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131, 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 Efficiency 5 in 1 Mug Heat Press Machine). In the maximal PAC performance pH was found to be around the neutral (3core 95mm 185mm XLPE Cable Armored Electric Cable; /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Exquisite Workmanship Rubber Shoe Vulcanizing Autoclave with Electric Heating) which determines the coagulation performance (50mm Qt450 Holdfast Hose Mender Casting for Mining). 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 (RF Wrinkle Removal IPL Hair Removal Skin Rejuvenation Beauty Salon Equipment with Filter).
Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle, charge and density, factors that influence directly in flock sedimentation.American Double Hung Thermal Break Aluminum Window in China(Retract Drill Mining Rock Thread Button Bit;2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink). 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 (Stainless Steel Waterproof Anti-Explosion Ik10 IP65 LED Linear Tube Light). Extracellular and surface-Fashion Design Steel-Wood Large Conference Table(Camera Fixing Screw,Small SMT Reflow Soldering Ovens for LED PCBA (A6)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Custom Jewellery 925 Sterling Silver Jewelry Diamond Stud Earrings), which can be one important cause of the increase in coagulant demand in algae-rich waters (New Filtration Small Size Large Processing Capacity Bag Filter).Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck(Custom Printing Polyester National Countryvinyl Nobori American Banner Flag), particularly humic susbtances. Humic substances are highly negatively charged (Workwear Winter Softshell Jacket Safety Clothing), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot Sale HD MD980asd Wireless Intraoral Camera with SD Card Storage). Maximal UV254removal was observed to be found around pH 6.0 (Control PCB Board for Hand Push Wheel Rangefinder). 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 (Dock Leveler Hydraulic Motor Hydraulic System and Power Pack).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids.
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