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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 (New Baking Tool Creative Customized Silicone Toast Cake Mold,Reliable Customized Precise Metal Stamping Punching Die Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (150-1000kg Commercial and Restaurant Cube Ice Maker Machine;Littlefuse IC Fuse Cartridge Ceramic Electronic Component Nanosmdc012f-2; AC4900ca). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Carbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washers). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Tempered Glass Roof),Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve. 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 (Waterproof Antislip PVC S Mat PVC Z Mat for Bath Swimming Pool Factory Price;Steel Drilling Water Well Filter / Bridge Slot Screen Pipe;Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars). However alum may result in high concentration of residual Al and is strongly affected by temperature (C-Type 2 Piece Tin Can Making Punch Press Machine) 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 (Kaishan YT23D Forging Air Leg Support Rock Drill Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer;Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control;Custom Ductile Iron Casting Parts Gray Iron Sand Casting;High Quality Sand Paper for Sand Machine Brush (YY-170);4-8mm Frameless Silver Mirror/Glass Mirror / Reflective Colored Mirror / Colored Mirror;Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu;Engineering Plastic Material).Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack(SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings;GMP Certified Collagen Softgel for Fish Collagen;m.glpurifier88.com;26000lm 200W LED High Bay Lamp Fixture for Gym House Factory) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor), and it has been suggested as a lake restoration measure.
Coagulation-Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)(Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine) and also by water chemistry (pH and alkalinity) (Corn Starch Foam Biodegradable Frozen Food Packaging Tray). 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 (Competitive Price Food Grade Sorbitol Liquid 70%). At pH of 6.0-7.Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence(Good Quality of 60t/D Wheat Flour Milling Plant,Energy Saving One Step Automatic Tritan Pet Blow Molding Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink(Bailian F Customized Server 2019 Hot Sell IPTV Server,100-400V DC Input Without Battery System 10000W 3 Phase Output Power Inverters with Solar Prority,insharevape.com).
In the tropical semi-20qt Portable Small Rotomolded Insulated Medical Cooler Box-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.Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale. 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
Color Coated Prepainted Aluminum Sheet/Coil, 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(Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug) and concentrations of total phosphorus (JAC 4X2 3ton 5ton Refrigeration Truck Freezer Box Truck;m.wetroyes.com) 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 (Aluminum Motor Housing Used in The Electromotor / Electric Motor Industry). 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). UV254Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)(DOM), mainly as humic substances (High Quality Medical Disposable Pen Type Blood Collection Needle).
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.)Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric, 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 toPlastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machinesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Filter Water Pp String Wound).430 Hot Rolled Stainless Steel Coil No. 1 Finish-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 (Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump). 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 UV254Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (American Double Hung Thermal Break Aluminum Window in China). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Grey Color Big Capacity Island Freezer for Frozen Foodd).
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(7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13). 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 (18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless). 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,Customized Embossing Logo Soft Flexible PVC Bar Mat, 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 (Used Fashion Summer Children′s Dress Unsorted;Longboard or Skateboard Ball Bearings 608zz 608-2RS;High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line;Head Support Travel Pillow). However,Concrete Stone Cutting Diamond Chain Saw on Sale.
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,Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor.RO Water Treatment Plant Water Purifying System Water Filter Machine, 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 (1000kg/Day Ice Making Machines Custom Ice Cube Machine). In the maximal PAC performance pH was found to be around the neutral (CNC OEM ODM Customized Car Housing Parts Machining Parts;Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Sports Bra Shock-Proof Gathering Stereotypes Bra) which determines the coagulation performance (Silk Flower For Decoration). 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 (2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price).
High and Low Temperature Humidity Chamber for Cycling Control, charge and density, factors that influence directly in flock sedimentation.Install High Density Hardie Ceiling Tile Fiber Cement Board(Stainless Steel Mesh Screen Automatic Self-Cleaning Filter;Hot Sale 250ml Green Dorica Glass Olive Oil Bottle). 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 (7). Extracellular and surface-Aerospace Industry Cutter Systems/ Equipment Cutting Plotter CNC Cutting Machine(China Log Debarker And Rounding Machine,Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide), which can be one important cause of the increase in coagulant demand in algae-rich waters (Round Vibrating Separator Machine - Round Vibratory Sieve).Custom Made Personalized Mini Pop Can Filling Machine(600ml Travel Sports Bicycle Water Bottle (HBT-037)), particularly humic susbtances. Humic substances are highly negatively charged (CNC Milling Parts), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Shielded Mini Ball Bearings with Anti-Rusty Stainless Steel Smr106zz). Maximal UV254removal was observed to be found around pH 6.0 (OEM Aluminum Housing Fuel Filter Housing for Truck/Train 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 (Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Contemporary Art Modern Wall Decor Giclee Artwork 3 Piece Canvas Print.
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