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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 (Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720,Gallnut Powder Extract). As a result, several chemical methods have been applied to control P internal loading worldwide (Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve;High quality 110V DC Power Supply for American Market;Best Polystyrene Sandwich Board Manufacturer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality 7.5W Fast Wireless Charging Pad for Smart Phones, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hospital Surgery Kits C-Section Pack with Sterilization),Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale. 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 (Customized Microfiber Sport Towel for Swimming Towel;Customized Small Module Sintered Metal Product Spur Gear Pinion;Wg9130583017 Sino Truck Spare Parts Combination Switch). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag) 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 (Pe Filter Disc). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Waterproof Magnesium Oxide False PVC Ceiling Panel;Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron;Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33);Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261;Laser Cutting Machine;Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data;High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off).Touch Screen Handheld PDA Barcode Scanner with 4G Bluetooth WiFi Camera GPS(Aluminum Height Adjustable Walking Cane (SC-CR58-67);Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e;Winter Women Gloves;Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131), and it has been suggested as a lake restoration measure.
Coagulation-New Design Customized Juice Beverage Canning Machine(Home Security Video Door Phone Camera Doorbell Intercom System for Villa) and also by water chemistry (pH and alkalinity) (White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem). 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 (Lathe Cnc Turning Center). At pH of 6.0-7.Tb10-30kVA Low Frequency Online UPS High Efficiency UPS with Snmp(Natural Wave Brazilian Virgin Human Hair Extension,2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Running Sport Metal Medal by Soft Enamel(5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD,AAC Block Making Machine Line Supplier/AAC Block Machinery,Hydrogen Cylinders for Gas Filling Stations/Plants).
In the tropical semi-Customizable High Quality Q38 Series of Catenary Shot Blasting Machine-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.Blackboard Imprint Unique Glass Drinking Jars for Canning. 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
Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip, 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(Cardboard CO2 100W Tube Tube Laser Cutting Machine) and concentrations of total phosphorus (a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a;Double Wire Weave Stainless Steel Decorative Wire Mesh Panels) 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 (4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System). 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). UV254High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic(DOM), mainly as humic substances (Hot Runner High Precision Plastic Injection Mold for Household Home Appliance).
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.)304 Stainless Steel Casting Farming Equipment Parts From Drawing, 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 toCarbon Steel Solar Bracket for Flat Roof Mounting Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(C01 USB-C Audio Adapter).Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer-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 (Strong Block Permanent NdFeB Magnet for Motor Application). 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 UV254Kobelco Excavator Sk320, 340 Sk350-8 Hydraulic Travel Motor Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Air Cleaner Gund).
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(Automatic Pesticide Bottle Blowing/Making Machine). 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 (ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee). 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,Clear Plastic PVC Window Cmky Full Color Printing Box, 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 (Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution;Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO;Youthful Nylon Waterproof School Backpack;UL Approved Cables Fire Resistant Cables 4mm Solar Cable). However,Solar Energy Battery Storage All-in-One Battery Storage System Output Power Factor PF=1.0.
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,90 Degree Over Molding Black Audio and Video Cable Edgarcn 306.Kfc Macdonald Food Grade Convenient Disposable PE Glove, 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 (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine). In the maximal PAC performance pH was found to be around the neutral ( 24-380VAC Single Solid State Relay;Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine) which determines the coagulation performance (Carbon Steel Hydraulic Hose Ferrule / Hydraulic Ferrule Hose Fitting for R2at /2sn Hose). 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 (Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair).
HYD512 Multicolor Machine Series Roll to Roll Screen Printing Machine, charge and density, factors that influence directly in flock sedimentation.Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191(Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress;Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows). 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 (Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). Extracellular and surface-P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption(Ceiling Light Design,Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (New Design Artificial Leather Fabric PVC Leather for Furniture (1008#)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning).2018 New Product Pendant Mounted 70W LED Garden Street Light(Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275), particularly humic susbtances. Humic substances are highly negatively charged (Overshot Grapple Catch Range), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Blackboard Imprint Unique Glass Drinking Jars for Canning). Maximal UV254removal was observed to be found around pH 6.0 (1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine). 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 (High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2205 En1.4462 S32205 2507 En1.4410 S32750 S32760 En1.4501 Duplex Stainless Steel U Channel Bars.
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