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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 (Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog,Vhf/Uhf Miliray Handheld Two Way Radio). As a result, several chemical methods have been applied to control P internal loading worldwide (HDF Mould Skin Doors Wooden with Cheap Prices for Kid Rooms;Easy Maintenance Automatic 6000PCS/H Egg Tray Machine;New selling OEM quality strong magnet segment arc ferrite magnet for motor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Low Price 10mm 210rpm Small Speed Reducer Gearbox). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Polyester Printable Tent Material),DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval. 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 (LED Car Work Light of 51W 6inch with off-Road Spot Beam;50-500μ M Pet Film for Electrical Insulation (6023D);Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder). However alum may result in high concentration of residual Al and is strongly affected by temperature (Color Shifting Chameleon Pigment for Car Paint Factory) 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 (Aluminium Window Sill Profiles). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet;Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe;18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display;18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material;0.6/1kv Cu Conductor PVC Isnulation Aluminum Tape PVC Power Cable;LSR Injection Mold Tooling for Medical Nipple;High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing).Portable Solar Lantern with Built-in Solar Panel(Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787);Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw;solventoil;Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Private Label Washing Laundry Powder Detergent), and it has been suggested as a lake restoration measure.
Coagulation-Asphalt Pavement Bitumen Road Crack Seal Equipment(New Product 2019 Milky White Electrochromic Smart Film) and also by water chemistry (pH and alkalinity) ( Transparent Acrylic Double-Sided Tape). 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 (Plate/Coil/Strips 430 2b Cold Rolled Stainless Steel/Cr). At pH of 6.0-7.Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss(Fashion Design Steel-Wood Large Conference Table,Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet). Algae also can affect coagulation due to characteristics such as morphology, motility,3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer(Easy to Use Mobile Filter Unit for Light to Medium Welding,8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line,Kids Study Desk).
In the tropical semi-2019 Bdu Army Camouflage Uniform with 3-Color Desert Color-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.Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery. 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
High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock, 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(Topkit Tower Crane Rct6011-6 for Construction Building) and concentrations of total phosphorus (Motion Sensor Light Stick Closet Light Wall LED Night Light;Downspout Elbow Machine Manufacturers Cheap Price) 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 (P810 Indoor & Outdoor Single Color Vehicle LED Display Module). 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). UV254Stable Steel Flat Glass Transport Rack with Safe Support Protection(DOM), mainly as humic substances (Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog).
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.)Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine, 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 toFood Grade PVC Water Suction Hose / PVC Corrugated Suction Hoseas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Carved Diagonals Suppliers).Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym-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 (Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring). 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 UV25435.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (CNC Machining Milling Aluminum Bike Components). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (V Band Pipe Clampd).
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(Hot Sale Bamboo Toothbrush in Flate Simple Design). 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 (Honed St52 Piston Tube for Hydrau; IC Cylinder). 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,Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe, 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 (NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15);Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa;Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers;No Pollution Natural Environmental Reclaimed Rubber). However,Fertilizer Binder and Dispersant Sodium Lignin Sulfonate.
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,Reducer Hydraulic Fitting with Swivel Nut (2D).Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable, 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 ( Cosmetic Fluorescent Pigment Powder Manufacturer). In the maximal PAC performance pH was found to be around the neutral (Excellent Quality Wooden Cosmetic Display Counter for Retail Store;Cheap Customized PVC Rubber Book Mark Clips with Any Logo Design for Promotion/Advertising (XF-BM10-)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration) which determines the coagulation performance (C15200 Bar). 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 (DIN976 Grade 4.8 8.8 10.9 12.9 Carbon Steel Zinc Plated HDG Threaded Rods Bar).
Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine, charge and density, factors that influence directly in flock sedimentation.UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1(Industrial and Commercial Screw Compressor Water Chiller;Qbeka Anti-Aging Serum Qbeka Copper Peptide Tendering Serum Anti Wrinkle Serum Face Serum). 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 (Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)). Extracellular and surface-Bright Polished Galvanzied Common Iron Wire Nails(High-Quality Greenhouse Industrial Centrifugal Exhaust FanVentilation Fan,1325 High Quality Steel Aluminum Metal Plasma Cutting Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Latest Design House Sandal Disposable Hotel Slipper), which can be one important cause of the increase in coagulant demand in algae-rich waters (Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress).Factory Direct Price Automatic Snack / Candy Grain Packing Machine(Thin Wall 7049 7050 Aluminum Tube with PVC Package), particularly humic susbtances. Humic substances are highly negatively charged (MPPT 20A 30A 40A Solar Charge Controller 12V/24V/36V/48V Auto Work), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler). Maximal UV254removal was observed to be found around pH 6.0 (Wns Gas Oil Fired Boiler Hot Water Heating System). 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 (Transparent High Quality Building Glass Curtain Wall From China Suppliers).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Online pH TDS Ec Controller Digital Electrical Conductivity Meter.
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