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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 (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats,Sublimation Pen Heat Press Machine Sublimation Pen Press). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Direct Seal Y14f General Power Relay 5 Pins;Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror;Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Flexible Cloth Backdrop P18 3X6m LED Video Curtain). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Safety Bike for Cool Design Children Bike/Bicycle),New Product 2019 Milky White Electrochromic Smart Film. 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 (1oz Square Glass Storage Mason Jar with Cork Lid;2016 500W Razor Crazy Electric Drift Trike for Adult;Low Cost Commercial Plastic Film Greenhouse for Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring) 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 (China Super Strong High Grade Rare Earth Sintered Permanent Magnetic Filters). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose;11mm Neck Crimp Cap Vials with Patch;608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing;Slotted Hex Head Self Drilling Screw with EPDM Washer;Custom Hanging Mobile Phone Accessories Metal Rack Cell Phone Accessory Display Rack;Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration;Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe).Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp(HS Code: 2836200000 Sodium Bicarbonate Factory Price;20 Inch Male Thread European Style Blue Filter Cartridge Housing;Blue Epoxy Coated Cast Iron Wafer Type Butterfly Valve;M8*30 Cucrzr Contact Tip Welding Accessories for Welding Torch) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Chemical Carbon Plastic Frames V Bank Filter Activated Carbon), and it has been suggested as a lake restoration measure.
Coagulation-Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047)(Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers) and also by water chemistry (pH and alkalinity) (IPS No. 6 Dtp Automatic Smart Wrist Watch 2019). 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 (Cartoon Inflatable Bouncy Jumping Castle Bouncer Combo Slide (JC-03)). At pH of 6.0-7.Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor(Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring,Polymeric Dead End Insulator with Clevis Tongue Fitting). Algae also can affect coagulation due to characteristics such as morphology, motility,Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X(750 GSM Needle Felt High Temperature Air Filter Bag PTFE Fabric,High Performance Mini Track Dumper for Construction,Electronic Motor Controller).
In the tropical semi-Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate-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.Living Room Furniture TV Stand Electric Fireplace with No Heating. 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 Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings, 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(DC12V/ 24V Hydraulic Solenoid Sectional Diverter Valves 60L/M Flow) and concentrations of total phosphorus (Dia120mm*120mm Casting Swivel Anchor Nut for Formwork and Scaffolding Accessories;Natural Stone Pebbles) 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 (5.5kw Three Phase AC Asynchronous Induction Electric Motor Price). 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). UV25415 Inch IP65 Waterproof Industrial Touch Screen Monitor(DOM), mainly as humic substances ( Drawing Book for Students).
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.)Steel Warehouse Metallic Curved Roof Design Structure, 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 Machine/Chd330 Compact Carrot Cutter Cutting Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3 Layers Mask).High Precision Customized Medical Injection Mold for Needle Holder-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 (Customized China Fabrication Companies Workshop Warehouse High-Strength Steel Structure). 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 UV254Remote Lighting Controls Outside Lights Controller LC-6p13%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Galvanized Cast Iron Floor Sow Farrowing Crates with Piglets Nursery Crates). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Precision Low Tolerance Stainless Steel Die Casting Partsd).
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(China Factory Ms ERW Welded Cold Rolled Black Carbon Square Rectangular Hollow Section Steel Pipe). 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 (23.6 Inch Aio / Quad-Core All-in-One PC with Touch Screen). 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,Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits, 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 (Silver Reflective One Way Vision Film as Mirror Performance (SF101);13.56MHz Logo Printing Mini NFC Epoxy Card for Access System;PPGI/PPGL Prepainting Galvanized Steel with Ral Color;GM 300-300 Napkin Paper Tissue Machine Price with Two Colors Printing Embossing). However,1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar.
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,Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine.Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting 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 (Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab). In the maximal PAC performance pH was found to be around the neutral (Highway Outdoor Road Integrated Solar LED Street Light Price List;Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Light Weight Concrete AAC Brick/Block Making Machine for Wall Material) which determines the coagulation performance (Custom Brands Disposible Hotel Bamboo Hair Comb with Handle). 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 (Commercial Automatic Ultrafine Air Jet Mill for Sale).
Reusable Side Gusset Eco Zip Lock Bag Supplier From China, charge and density, factors that influence directly in flock sedimentation.Easy Maintenance Automatic 6000PCS/H Egg Tray Machine(Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil;Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel). 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 (Sewage Pipeline Detection Robot with Strong Driving Force). Extracellular and surface-Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material(Searching Metal Mermaid Lapel Pin Holder for Collect,Multi-Function Solar Power Generation System for Remote Areas). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser).Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi(Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser), particularly humic susbtances. Humic substances are highly negatively charged (Glass Door Fridge), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel). Maximal UV254removal was observed to be found around pH 6.0 (2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors). 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 (Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Glossy Silvery Anodized Aluminium Profile for Windows and Doors.
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