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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 (A4,Automotive Parts Factory & Manufacturer). As a result, several chemical methods have been applied to control P internal loading worldwide (High Efficiency Hook Type Shot Blasting Machine for Sale;Non-Toxic RTV Silicone Sealant of Full Automatic Machine;High Tensile Forged Chain with Conveyor for Conveying System). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (M5 SMD with Internal Blind-Hole Thread with Pin (groove)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Agricultural Full Spectrum LED Grow Lighting for Commercial Horticulture),Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter. 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 (Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile;Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed;Customized Wire Mesh for Decorative Garden Fence). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fan Cooling Oval Design Commercial Cake Display Showcase Fridge) 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 (Asian Type Nofrost Evaporator Automatic Fin Placing Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (China Qingdao Factory Interlocking PVC Garage Floor;Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm;Double Arm Medical Pendant for Anesthesia (HFP-DS240/380);High Quality Galvanized Welded Wire Mesh Panel Roll;Custom High-Elastic 2mm Newest Women′s Neoprene Gym Tops Vest Fitness Waistcoat;Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event;Ce Eco-Friendly 24V Electric Motor Operated SS304 Water Flow Control Valve for Drinking).Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508(Incoloy 825 Pipe for Industry Application;New Type Portable 380V Electric Winch in Stock;Single Mode Fiber Patch Cable FC St LC Sc Connectors Fiber Optic Patch Cord;Custom A4 Size Plastic PP Clear File Button Folder) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hook Vintage Weathered White Wall-Mounted Wood Coat Rack with Chalkboard Labels), and it has been suggested as a lake restoration measure.
Coagulation-Transparent High Quality Building Glass Curtain Wall From China Suppliers(250ml Empty Refillable Pet Material Plastic Shampoo Bottle) and also by water chemistry (pH and alkalinity) (Laparoscope Instrument Laparoscopy Set for Ectopic Pregnancy Surgery). 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 (Airbrush A Batteria). At pH of 6.0-7.Professional Produce Dmp-430A Vacuum Tray Sealer(Industrial Paraffin Wax/Powder/Slab/Paraffin Wax Chemical Formula,Ouwave HVAC Scent Fragrance Systems Aroma Diffuser Electric Scent Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Cation Printing Effect Micro Fleece, Jacket Fabric (nautical blue)(120 Grit Sand Blasting Media/Sandblasting Abrasives/Almandite/Garnet Sand 80 for Waterjet Cutting,Ci/Di/Ss/C954 Al Bronze Body Double Flange Butterfly Valve Pn10 Pn16 Pn25,Frp Anchor Rod).
In the tropical semi-Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique-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.Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace. 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
Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage, 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(Ad-P720 Hot-Selling Perfume Glass Bottle 100ml) and concentrations of total phosphorus (Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair;Hocus Pocus Shirt) 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 Grade U2 U3 Stud Link Anchor Chain with Factory Price). 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). UV254Construction Equipment Full Automatic Concrete Block Making Machine(DOM), mainly as humic substances (Diesel Fuel Leak off Pipe for Mercedes-Benz).
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.)Customized Sheet Metal Products, Stamping Parts, Welding Parts, 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 toRexroth Hydraulic Pump A8V55/80/107 Replacement Spare Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mc4 Parallel Connector).Cartoon Design Decorative PVC Sheet for Wall Panel Moulding-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 (Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire). 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 UV2544 Fibers Wall-Mounted FTTH Distribution Box%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Ly1-10 Malaysia Manual Interlocking Brick Making 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(Modular Functional L Shape Living Room Leather Sofa). 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 (Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone). 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,4-20mA Signal Steam Directional Flow Pneumatic Control Valve, 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 (Transparent 240W SMD 3030 Outdoor LED Flood Lamp;ISO Factory of Disc Cutter for Tunnel Boring Machine;CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut;Plastic PVC/WPC Foam Board/Sheet Extrusion Line (SJSZ-80/156)). However,Non Woven Wheel for Stainless Steel Polishing and Grinding.
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,30cm Round Clear Plastic Pot Plant Trolley.Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board, 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 (Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966). In the maximal PAC performance pH was found to be around the neutral (Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture;Dac34640037 Wheel Bearing /Automotive Bearing/ Hub Bearing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Aluminum CNC Al5052 / Al6061 / Al6063 Machining Turning Parts for Mil-Spec Electronics) which determines the coagulation performance (Glazed Roll Forming Machine). 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 (Electric Multifunction Motorized Lifting and Rotated Medical Equipment Product Fth-005).
Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution, charge and density, factors that influence directly in flock sedimentation.AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale(Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds;2019 Henan Factory Manufacturer Industrial Wood Chipper Wood Chipper Shredder). 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 (Banbury Rotors 3L Lab Plastic and Rubber Mixer Machine). Extracellular and surface-Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale(High Quality Monument Snow Black Granite Tombstone Wholesale Memorial,P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (27.5er Sram 12speed carbon Mountain Bike with Air Suspension Fork), which can be one important cause of the increase in coagulant demand in algae-rich waters (Ce Approved Gobal Warranty 200kVA 100kVA 50kVA 25kVA Diesel Generator Price).PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector(Aluminum/Aluminium Foil/Coil for Retort Pouch/Bag/Stand-up Pouch A8079/1235/8011-Soft 5.9/6 Microns), particularly humic susbtances. Humic substances are highly negatively charged (Electric Galvanized Iron Wire), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Purity Medical Psa Oxygen Generator/Concentrator Manufacurer with Low Cost). Maximal UV254removal was observed to be found around pH 6.0 (925 Fashion Silver Jewelry with Zircon Set Ring Wholesale). 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 (Full Automatic Egg Tray Manufacturing Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120).
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