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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 (Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer,Precision Sand Casting). As a result, several chemical methods have been applied to control P internal loading worldwide (Building Hot Rolled C Purlin C Channel Steel Price;Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector;PP Surface Self Adheisve Roof Underlayment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (French Fries Fryer),European VDE Schuko 3-Pin Waterproof IP44 Power Plug. 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 (Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price;Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing;Jbz-22D Automatic High Speed Paper Cup Forming Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature ( PN20)) 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 (Heat Resistant Storage Container Bamboo Cover Food Jar). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Chicken Farm Poultry Battery Cage System for Layer;2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door;Wood Based Powdered Norit Activated Carbon Price;Cheap Prise Solid Carbide Reamers for Drilling Hole Factory Outlet;High Quality Cheap Price Use Work Coverall Custom Working Safety Uniform;UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode; 1 High Alumina Ceramic Ball with High Quality).Hot Most Industrial Outdoor Trampoline, Commercial Trampoline Park for Sale(Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17;Color Coated Prepainted Aluminum Sheet/Coil;Amusement Parks RFID silicone bracelet;High Quality Wooden Cabinet Design Shoe Display Unit for Shop) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Easy Installation Modern Luxury Container House), and it has been suggested as a lake restoration measure.
Coagulation-12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires(Automatic Canned Aloe Vera Cube Dicing Cutting Cutter Machine) and also by water chemistry (pH and alkalinity) (Intelligent Dry-Type Transformer Monitor with Plastic Cover). 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 (Atlas Copco Compressor Spare Parts Service Kit CV-Osv 2906096100 2906096300 2910300600). At pH of 6.0-7.China Supplier Customized Polish Storage Wall Mounted Wine Rack(Organice Ball Fertilizer Granulation Machine,Hotel Waffle Slipper From China Supplier (DPF2437)). Algae also can affect coagulation due to characteristics such as morphology, motility,Customized Waterproof Backpack Canvas Laptop Bag(USB a to Lightning Quick Charge Data Cable,Outdoor Fitness Equipment Gym Chilren′s Teeterboard,12VDC Tl-14f3 High Power Relay Customized 5pin PCB Type).
In the tropical semi-75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display-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.Square Home Sofa Throw Decorative Pillow Case Cushion Cover. 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
Stage LED Bar 54PCS*3W RGBW DJ Disco Stage Lights, 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(40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer) and concentrations of total phosphorus (Warehouse Storage Industry Rack Mezzanine Floor Platform;Warm Colour Bedding Vietnam) 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 (Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair). 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). UV254Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat(DOM), mainly as humic substances (Hot Sale Pet Strap Straps Strapping Band Machine/Extrusion Line/Extruder).
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.)Valve Wheel Adjustable Hydraulic Impact Torque Wrench, 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 toElectroplated Diamond 200mm Circular Saw Blade for Concrete Cuttingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(PPR White Pipe Fitting Equal Elbow 90 Degree for Water Supply).CRI-4000 Common Rail Injector Test Bench for Bosch, Denso, Delphi, Siemens-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 (Online Hot Sale 5 Tier Silver Home Organizer Shelving). 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 UV254CNC Deep Machining Aluminium TV Frame Part with Anodization Surface%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (French Parfum Glasss Perfume Bottle with Water Tramsfer Printing Decoration). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.hyrubbers.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(Wholesale Alibaba Custom Personalized Metal Gold Plated Philippines Country Flags Lapel Pins). 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 (Top Quality Hydraulic At170 Breaker 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,Quality Medium Stapler with Staples Remover, 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 (HDPE PE Pipe Production Line/ PPR Pipe Production Line;Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch;Matt Print Foil Coffee Bags with Valve Flat Bottom Zipper;Kevlar Gland Packing). However,Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump.
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,Eco Brava Small Mud Interlock Brick Press Machine.Gi Square Pipe Ms Hollow Steel Tube Weight Per Meter, 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 (Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630). In the maximal PAC performance pH was found to be around the neutral ( BBQ;Custom High Quality Winter Newsboy Beret IVY Cap for Men). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Customized Various Aluminum Hardware Fastening/Real Accessories) which determines the coagulation performance (A4 Paper 80gr). 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 (China OEM ABS Clear Plastic Injection Molding).
Agricultural Sprinkler Irrigation System Oscillating Impact Sprinkler for Garden, charge and density, factors that influence directly in flock sedimentation.Full Automatic Sachet Cartoning Pack Machine (ZH100)(Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes;Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen). 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 (Micro Inch Finishes for High Precision Grinding Lapping Metal Non-Metal Part). Extracellular and surface-Printed Coated Bulk 100d Filament CVC Poly Cotton Fabric Uniform Army Green Workwear(Cheap Aluminum Bracket,The Factory Sells Low Price and High Quality Desulfurizer Powder). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Flanges Male Female Fittings Assembled with Flexible Metal Hose), which can be one important cause of the increase in coagulant demand in algae-rich waters (Kid′s PVC Rainproof Rain Jacket with Full Print).New TF Card Head Fone Retractable Audifonos PARA cellular Bluetooths Headphone(OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized), particularly humic susbtances. Humic substances are highly negatively charged (Handrail Stanchions For Balconies), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Quality Reliable Scrap/Waste Tyre Recycling Plant to Make 30-120mesh Rubber Powder). Maximal UV254removal was observed to be found around pH 6.0 (Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch). 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 (Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope.
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