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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 (Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2),Black Chicken Wire). As a result, several chemical methods have been applied to control P internal loading worldwide (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131;Home Security Video Door Phone Camera Doorbell Intercom System for Villa;White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Natural Wave Brazilian Virgin Human Hair Extension). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CNC Precison Red Painting Titanium Alloy Machinery Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industrial Top Performance CNC OEM Aluminum Extrusion Profile),I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds. 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 (2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds;5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD;AAC Block Making Machine Line Supplier/AAC Block Machinery). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Promotional Soft Cover Children Music Book Printing) 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 (yishanjiushe.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale;Cardboard CO2 100W Tube Tube Laser Cutting Machine;a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a;Replacement EPE Eppensteiner Filter Element (8260P10S000P);2019 Korea Salon Grade Professional Ceramic Big Wave 2 Inch Medium Length Curly Hair Curler;Stainless Steel High Quality Cashier Counter Table for Shopping Center;4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System).New Design Contact Infrared Baby Ear Thermometer Jl0158(Hot Runner High Precision Plastic Injection Mold for Household Home Appliance;Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W;Cy Brushless DC Motor 900W Used in Electric Tricycle;Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2018 Hot Selling Gold Stainless Steel High Bar Chair), and it has been suggested as a lake restoration measure.
Coagulation-Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag(Carbon Steel Solar Bracket for Flat Roof Mounting System) and also by water chemistry (pH and alkalinity) (Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet). 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 (Portable Rugged Android6.0 RFID PDA Handheld NFC Reader). At pH of 6.0-7.OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector(Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench,Strong Block Permanent NdFeB Magnet for Motor Application). Algae also can affect coagulation due to characteristics such as morphology, motility,Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine(New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds, Telehandler Price,50mm Graphite Electrode Exporter Hot Sale Product).
In the tropical semi-Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM-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.Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects. 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
Permanent Magnetic Grid for Europe Market, 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(China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining) and concentrations of total phosphorus (High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts;Funny Car Accessories) 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 (Youthful Nylon Waterproof School Backpack). 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). UV254New Fitness Commercial Exercise Spinning Bike(DOM), mainly as humic substances (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine).
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.)Ce Approved Disposable Paper Mask, 2 Ply Beauty Face Mask, 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 toBlack Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chairas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Deep Cycle Lithium Battery 12v).Vertical Gas Boiler for Water Heating in Biogas Plant-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 (Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). 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 UV254CO2 Laser Engraving Cutting Machine for Acrylic%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Productsd).
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(Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning). 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 (Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275). 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,Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts, 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 Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic;Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine;High Stability Elastic Tapes Automatic Screen Printing Machine). However,VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A).
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,304 316 1.4301 1.4404 Stainless Steel Angle with Sharp Edge.up-Down Table 1390 100W CO2 CNC Laser Cutter Machines, 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 Quality Custom Design China Plastic Injection Molding Factory). In the maximal PAC performance pH was found to be around the neutral (Pre-Heated Copper Coil Pressure Solar Water Heater Equipment;Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hot Selling SAA Rcm Listed CCT Changeable LED Down Light) which determines the coagulation performance (Resveratrol 50% 98%Polygonum Cuspidatum Sieb. Et Zucc). 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 (Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades).
Glass Bakeware Dish Oval Glass Baking Dishes Deep Glass Roaster, charge and density, factors that influence directly in flock sedimentation.Superior Fabric Core Conveyor Belts Vulcanizing Press From China(Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle;20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen). 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 (Manufacturers Supply Through Hole Right Angle USB 1394 Connectors). Extracellular and surface-China Supplier PPGI Coils for Construction Materials(Cnc Router 6 Axis,Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Factory Directly Sale Virgin Kraft Liner Paper Machines), which can be one important cause of the increase in coagulant demand in algae-rich waters (Special Offer Stock Primary School Uniform Shirt for Boys).Auto Parts Engine Cooling Air Conditioner OEM 88450-26120(12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery), particularly humic susbtances. Humic substances are highly negatively charged (Cavitation Rf Vacuum Body Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult). Maximal UV254removal was observed to be found around pH 6.0 (Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts). 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 (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Mild Price A36 1.0425 ASTM A214 Seamless Carbon Steel Tube.
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