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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 ( Square Plate,Ready Concrete Mixer Type CMP750 Planetary Concrete Mixer for Precast Factory). As a result, several chemical methods have been applied to control P internal loading worldwide ( Muffin Pastry Box;Silver Reflective One Way Vision Film as Mirror Performance (SF101);13.56MHz Logo Printing Mini NFC Epoxy Card for Access System). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (PPGI/PPGL Prepainting Galvanized Steel with Ral Color). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Innovative 2A/B Contact Form Power Relay for Electricity Meter, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (New Condition and Ce Certification Iron Frame Belt Transfer Beveling Machine),ODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Works. 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 (Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab;Highway Outdoor Road Integrated Solar LED Street Light Price List;Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid). However alum may result in high concentration of residual Al and is strongly affected by temperature (Light Weight Concrete AAC Brick/Block Making Machine for Wall Material) 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 (Traffic Removable Car Parking Bollard for Public Security Control). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Commercial Automatic Ultrafine Air Jet Mill for Sale;Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil;Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel;Sewage Pipeline Detection Robot with Strong Driving Force;Stacking Storage Box;Multi-Function Solar Power Generation System for Remote Areas;Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine).Filter Fiber Car Engine Cabin Air Filter for Mazda(Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser;Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser;Tractor Lawn Mowers Seat;Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors), and it has been suggested as a lake restoration measure.
Coagulation-Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory(Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20)) and also by water chemistry (pH and alkalinity) (Kunlun Paraffin Waxes From Petroleum Made in China). 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 (China 15kva Servo Controlled Voltage Stabilizer). At pH of 6.0-7.Embroidery Sequins Lace Mesh Lace Fabric Embroidery Sequins Lace Mesh Lace Fabric(Ce Certificate Factory Provide Drink Water Vending Machine,Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X). Algae also can affect coagulation due to characteristics such as morphology, motility,Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC(CNC Machine Linear Guide Accordion Bellows Cover,Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage,Variable Frequency DC 24V Automatic Quiet Submersible Aquarium Pumps for Waterfall Flow 5000L/H).
In the tropical semi-40mnb High Quality 40teeth Grass Brush Cutter Blade-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.High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line. 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
49 Electric/Electrical Synchronous AC Gear Motor for Stage Light/Oven, 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(School Exercise Book Making Machine 2.3.4 Colors) and concentrations of total phosphorus (Syrup Piston Filling/Cream Liquid Bottle Filling Machine;Girls Parka Coat) 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 (LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031). 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). UV254Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone(DOM), mainly as humic substances (Fast Thermal Cycling High Heat Temperatures Resistance 99% Alumina Ceramic Insulator Rod).
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.)Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D, 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 toLow Price Promotional Concrete Cement Mortar Plaster Pump Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hydraulic Fitting Seals).Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801-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 Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Use). 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 UV254Bsg-901 High Quality Cheap Price Soccer Goal Nets%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel Custom Made LED Backlit Letter Signsd).
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 Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger). 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 (DMX New Design Stage DJ Disco 1024p Light Controller). 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,Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture, 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 (Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water;P10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Edited;Outdoor Food Meal Heating Bag for Travelling and Camping;Credit Card Protector Rfid Blocking). However,Electrical Insulator Fibreglass Separator for Lead Acid Battery.
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,High Quality Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment.Video Endoscope with 5.5 Wireless, 3.9mm Camera Lens, 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 (Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra). In the maximal PAC performance pH was found to be around the neutral (Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508;430 Black Mirror Decorative Stainless Steel Sheet in Foshan). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Door) which determines the coagulation performance (4 Amino Phenyl Acetic Acid). 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 (Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle).
3 Fold Telescopic Ball Bearing Drawer Slide Rail, charge and density, factors that influence directly in flock sedimentation.Single Quartz Tube Medium Infrared Carbon Fiber Heater(Atex Approved Level Measuring Instrument Level Sensor; LPG Hose Best Choice for Home Use). 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 (High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire). Extracellular and surface-High Quality Antibiotics Powder Enrofloxacin CAS 93106-60-6(500L Jam Making Machine Strawberry Jam Cooking Pot Jacketed Kettle for Jam,Wholesale Foldable Desk Silicon Mobile Phone Stand). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool).Yh1650 15′′ Retractable Cable Wire Trigger Key Lock Gun Lock( Table Gas Stove), particularly humic susbtances. Humic substances are highly negatively charged (Double Lip Seal), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services). Maximal UV254removal was observed to be found around pH 6.0 (Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price). 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 (Supporting DDR4 RAM Intel Core I5 Mini PC Computer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring.
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