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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 (Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick,Bronze Casting Worm Gear with CNC Machining). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized Wholesale Waterproof Crossbody Chest Bag Backpack Sling Bag Women Messager Shoulder Bag;Light Weight FRP XPS Composite Panel for Mobile Home Construction;OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cylindrical 3 Phase Power Capacitor),High Speed LDPE Polyethylene Plastic Film Extrusion 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 (Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt;Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor;Seu 2*8 AWG Concentric Service Entrance Cable). However alum may result in high concentration of residual Al and is strongly affected by temperature (Acrylic Crystal and Enamel Flamingo Bracelet Fashion Jewelry) 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 (roll crusher). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W;Auto Electric Car Step Siliding Step with Ce Load 250kg;China Manufacturer Cement Plaster Storage Pressure Tank Container;China Automatic Round Stainless Steel Bar Peeling Lathe Machine;ISO Certified 100% Natural Bitter Gourd Extract for Treating Hepatitis;Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring;Activated Carbon Pellet Manufacturer Used for Gas Treatment).Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event(Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service;Auto Starter 0001230002 12V 3.0kw 11t for John Deere;Ddq Cold Rolled Thin 201 Stainless Steel Strip for Springs;Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (New Product High Quality Home Smart Wireless Video Doorbell Camera), and it has been suggested as a lake restoration measure.
Coagulation-Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe(Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier) and also by water chemistry (pH and alkalinity) (1kVA/2kVA/3kVA/4kVA/6kVA/8kVA/10kVA/15kVA/20kVA/30kVA Single Phase Online UPS). 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 (Uhmwpe Mooring Rope Manufacturer). At pH of 6.0-7.Caprolactam Grade Ammonium Sulphate (21%Min)(12oz Dispossable Ripple Wall Paper Cup with Good Insulation,Naked Mango Premium E-Liquid for Electric Cigarette). Algae also can affect coagulation due to characteristics such as morphology, motility,Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm(M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter,Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM,Best Soft Bristle Toothbrush).
In the tropical semi-NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor-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.Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles. 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
19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment, 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(Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block) and concentrations of total phosphorus (Kynko Li-ion Cordless Drill with 18V Battery (KD30);Matte Adult Graduation Caps) 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 (Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester). 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). UV254Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw(DOM), mainly as humic substances (AC Magnetic Contactorstc-40 (GMC) Electric Contactor).
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.)100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men, 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 toDn630mm Plastic Pipe Butt Fusion Welding Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Pressure Washer Excellenct Quality Automatic Car Wash Machine Price).Concrete Road Cutting Machine, Road Cutter, Road Saw Machine-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 (12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools). 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 UV254Soyo Energy Aluminum Alloy Solar Ground Mounting System%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel Ptfe Hosed).
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(Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service). 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 (Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price). 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,Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561), 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 (Agriculture Cultivator Springs Double Spring Tines 3.5-12mm;Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip;Wholesale High Quality USB Charging Data Cable for Original Apple iPhone 7 Charger Cable;Drum Roller Conveyor). However,New Mini Loader Radlader Mini Zl936 Wheel Loader.
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,Fein Titanium Bi-Metal Oscillating Saw Blade.Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863, 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 (Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module). In the maximal PAC performance pH was found to be around the neutral (Long Service Life Smooth Lead Screw Tr3.5X0.61;Computerized CNC Turning Machine Metal Lathe Price Ck63L). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (8mm PVC Coated Galvanized Steel Wire Rope for Lifting) which determines the coagulation performance (PP Surface Self Adheisve Roof Underlayment). 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 (Manufacture RP HP UHP Graphite Electrode 300mm 350 with Nipples for Smlting).
FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound, charge and density, factors that influence directly in flock sedimentation.Handrail Fitting / Stainless Steel Round & Square Tube Connector(Good Quality UPS Batteries 12V 65ah for Burglary Protection System;Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration). 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 Tube Electric Heater Industrial Immersion Cartridge Heater). Extracellular and surface-Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car(Timber Sample Folder,Wholesale Events 6FT Wood Dining Round Table). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Wall Fan 3 in 1-Competitive Price), which can be one important cause of the increase in coagulant demand in algae-rich waters (CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine).BRT Gasoline Log Splitter 22 Ton Firewood Processor(High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws), particularly humic susbtances. Humic substances are highly negatively charged (nsen-valve), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale). Maximal UV254removal was observed to be found around pH 6.0 (Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition). 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 ((Made in China gold sellers) SPA Swimming Pool Water Filter Pump).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Android Data Cable Mobile Phone USB Cable Mobile Phone Cables.
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