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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 (Qbeka Anti-Aging Serum Qbeka Copper Peptide Tendering Serum Anti Wrinkle Serum Face Serum,Automatic Cooling Ice Block Machine Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097);1325 High Quality Steel Aluminum Metal Plasma Cutting Machine;Latest Design House Sandal Disposable Hotel Slipper). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (No Projector Interactive Whiteboard),Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700. 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 (Thin Wall 7049 7050 Aluminum Tube with PVC Package;1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler;Wns Gas Oil Fired Boiler Hot Water Heating System). However alum may result in high concentration of residual Al and is strongly affected by temperature (Transparent High Quality Building Glass Curtain Wall From China Suppliers) 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 (Microfiber Pu Leather). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Flat Compression Injection Mould Die Spring/Standard Coil Spring with Rectangular Section;3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist;Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken;ACP/ACP Sheet/Aluminum Composite Panel Manufacturer;Cotton Canvas Polyester Rubber Chevron Conveyor Belt;Yellow Corrugated PE-Al-PE Gas Pipe with Size 16mm to 32mm;New Business Projects Mobile 5D Cinema with High Quality).Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C(5 Inch Diamond Protected Teeth Blades for Cutting Granite;Custom Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt;mypestkiller;Steel Structure Roofs System TPO Waterproof Membranes) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Water Heater Single Head Shrinking Machine), and it has been suggested as a lake restoration measure.
Coagulation-Water Play Equipment Inflatable Gym Air Track Mat(Co-Extrusion Extruder Single Screw Auxiliary) and also by water chemistry (pH and alkalinity) (2019 Unique Design UV Printing Phone Case for Apple iPhone 8). 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 (www.ironwiremeshfactory.com). At pH of 6.0-7.Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine(Immersion Gold 94V0 Circuit Board Assembly Saving Energy Electrical PCB,Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker). Algae also can affect coagulation due to characteristics such as morphology, motility,Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes(OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer,Sun Cover Heat Resistance Shade Privacy Screen,m.realtopmachinery.com).
In the tropical semi-Gear Operated Cast Iron Wafer Type Butterfly Valve-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.Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair. 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
Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835, 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(Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic) and concentrations of total phosphorus (Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow;ID 450-1200mm PVC PE Plastic Pipe Cable Electric Conduit Extrusion Making Machine Factory) 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 (Very Cute Baby Gift Packing Shopping Carrier Paper Bag). 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). UV254Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall)(DOM), mainly as humic substances ( Cookware Set with Hammer Pattern).
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.)Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container, 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 toBalcony Terrace Roof Canopy with Aluminum Frameas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Heavy Duty Wood Engraving Machine CNC Router).Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid-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 ( High Temperature Boiler Steel Pipe Tube ASME SA335 P22 P 91). 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 UV254Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Used 48cavity Cool/Hot Runner Cutlery/Spoon Plastic Injection Mould). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.asiamzsteel.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(Surface Paiting Line UV PU Water Base Spraying Robot Arm). 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 (Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box). 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,Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer, 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 (The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture;DIN7504 Stainless Steel Self Drilling Drywall Screw; Construction Pipes Price;Scratch and Stain Resistance Quartz Stone Kitchen Sink with Single Bowl). However,Pre-Painted Color Coated Aluminum Coil and Strip.
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,1.0L Chinese Steam Cooking Type Electric Tea Kettle with Pot.Back Bar Beer Cooler, 2 Door Beverage Glass Chiller Bg-208h, 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 (Synthetic Filament Spunbonded and Needlepunched Nonwoven Geotextiles). In the maximal PAC performance pH was found to be around the neutral (DIY Modern Metal Wine Bottle Rack Organizer;Circular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (3-Wheel Motorcycle with 1500W Motor and EEC Certificate) which determines the coagulation performance (Products). 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 (10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom).
China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining, charge and density, factors that influence directly in flock sedimentation.Best Price Slewing Ring Bearings for Crane Wind Turbine System(Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor;Patient Modular Monitor with Wireless Network and Wire Network). 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 (25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake). Extracellular and surface-Custom China Supplier Stainless Steel Precision Casting Throttle Valve(Solid Tungsten Carbide Rods,Medical Infusion Pump for Human and Veterinary with Fluid Warmer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Ce Certificated Acm-60 PTFE Powder Grinding Mill), which can be one important cause of the increase in coagulant demand in algae-rich waters (Buildings Materials ASA PVC Roof Tile Roofing Sheet).China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube(Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging), particularly humic susbtances. Humic substances are highly negatively charged (5 LCD Rearview Monitor Night Vision Backup Mini Camera), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall)). Maximal UV254removal was observed to be found around pH 6.0 (Auto Crane Electrical Overhead Cable with Steel Wire). 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 (Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Welding.
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