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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 (Environmental Protection Material PLA Sheet for Cup Lid Tray Forming,Aluminium/Aluminium Extrusion for LED Lighting with ISO9001: 2015 Certificated). As a result, several chemical methods have been applied to control P internal loading worldwide (Amusement Park Best Electronic Washing Ball Clean Dry Machine Cleaning Ball Machine;Bestsub Sublimation Square Ceramic Coaster W/ Cork (CBZ24);8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Electrolytic Tinplate Coils),Portable Marking Equipment System Laser Wire Marking Machine Price. 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 (Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw;Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine;Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector). However alum may result in high concentration of residual Al and is strongly affected by temperature (Good Performance High Precision Thrust Roller Bearing (29292)) 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 (2019 Fast Speed Electric Mobility Scooter Wholesale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (30% Al2O3 Content Yellow PAC for Wastewater Treatment;ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling;50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale;Precise Profile Wire Universal Rolling Mill;60x60 Square Steel Pipe Tube;Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant;Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift).3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten, Kitchen Utensils, Dutch Oven(Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag;Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer;Mini Electric Wire Rope Hoist PA 1000 Electric Winch;Classic Cafe Dining Chair with High Quality/Grey/Arm Chair) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould), and it has been suggested as a lake restoration measure.
Coagulation-200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter(Cosmetic OEM Gold Pet Foam Bottle for Cosmetic Packaging and Face Cleam) and also by water chemistry (pH and alkalinity) (Automatic Turntable Continouse Blast Cabinets Belt Sandblaster Sandblasting 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 (Mushrooms Vacuum Cooling Machine). At pH of 6.0-7.Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe(220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Light,Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)). Algae also can affect coagulation due to characteristics such as morphology, motility,Thermal Transfer Waterproof Tearproof Matt Silver Pet Label(High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator,Custom Machining Service Machined Parts High Precision CNC Milling Process,Custom Heat Press Gold Foil Stamping Logo Real Leather Patches Labels for Denims Jackets Clothing).
In the tropical semi-SMD P4 Outdoor Full Color Rental HD LED Display-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.Toroidal Inductor Coils Tlc/1A-221m-00 for Speaker Use., Radio etc Use.. 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
Smooth Surface Black HDPE Sheets for Wastewater Treatment, 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(Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest) and concentrations of total phosphorus (Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter;Bmw Stereo Upgrade) 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 (Permanent N50 Tiny Mini Neodymium Magnet for Sale). 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). UV254Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel(DOM), mainly as humic substances (High-Grade Hemp Rope Hanging Grain General Twine Hanging Grain Spot).
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.)High Precision Injection Molding Plastic Parts in China (STK-PL-1055), 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 toPink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dressas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(chinajssl).Fan Cooling Oval Design Commercial Cake Display Showcase Fridge-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 (Home Furniture Metal Chair Grey Velvet Dining Chair). 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 UV254Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Swing Check Valve Stainless Steel Type Non Return Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.foismet.comd).
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(Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250). 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 (C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm). 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,CNC Machine Linear Guide Accordion Bellows Cover, 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 (Stainless Steel Checkered Plate 304 316L 410 Floor Material;Snowkey Meat Processing Cooling Flake Ice Making Machine;Custom Aluminum Die Casting Parts for Medical Equipment;Modern Style Cheap Price Curved Single Bathroom Vanity). However,White/Gray Colors U-PVC Water Supply Pipe for Plumbing System.
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,Microfiber Towel Quick Dry Towel Set for Beach, Travel, Swim, Pool, Camping, Outdoors and Sports.Seamless Steel Rolled Ring, Forged Steel Rings for Large Diameter, Manufacturer of Slewing Ring, 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 (Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home). In the maximal PAC performance pH was found to be around the neutral (J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter;2018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Nylon Flashing LED Dog Leash with Night Light) which determines the coagulation performance (G80 High Tensile Alloy Drag Lifting Steel Link Chain). 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 (Aluminium Spigot Lighting Truss).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Sesame Almond Cashew Nut Peanut Butter Making Processing Machine.
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