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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 (4 Stage Ture HEPA Filter Ionic Air Purifier with 4 Fan Speed,Galvanized Equal And Unequal Steel Angle). As a result, several chemical methods have been applied to control P internal loading worldwide (Molten Steel Ladle for Casting;CCTV 8.0MP 4K Video Security Surveillance IR Dome Ahd Camera;Mini CNC Mill Laser Cutting Machine 5 Axis Routers). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (095000 6366),Vci PE Film for Ferrous Metal with Anti-Rust Performance. 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 (RO Water Plant System Water Sediment Filter Machine;15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale;Removable Tissue Cutting Machine (double channels)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Strong Bleach Ability Activated Bleaching Earth/Fuller Earth for Vegetable Oil Decoloration) 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 (Food Metal Detector Detect All Kinds of Metals Broken in Food and Textiles SA810). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould;High Precision Mini Micro Button Load Cell;Supersnow Frost Free Combined Deep Island Commercial Supermarket Display Freezer;HPL Board Top Adjustable Coffee Dining Table;China flexible hydraulic hose;Gi Square Pipe Ms Hollow Steel Tube Weight Per Meter;for Communication Telecom Rg Series 50 Ohm Coaxial Cable Rg58 Cable).Solar Garden Peacock Stake with Solar Light for outdoor Decoration(Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper;Anti Slip Toe Protection Safety Hospital Clog Shoes;Fluorine Lined/PTFE Lining Stainless Steel A351 CF8m Lug Butterfly Valve;Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Prepainted Galvanized PPGI Corrugated Steel Roof Plate Roofing Sheet Best Price), and it has been suggested as a lake restoration measure.
Coagulation-Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8(Low Ceiling Tilt Car Parking Lift Space Saver) and also by water chemistry (pH and alkalinity) (12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires). 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 (Custom Luxury Leaves Patten Printed Beach Sun Umbrella with Trim/Tassel/Fringe). At pH of 6.0-7.4.3 IPS Display 1080P Dash Cam 12 Mega Pixel Rear View Mirror with Parking Monitor, G-Sensor( Digital Thermometer E278,Matching 3kw). Algae also can affect coagulation due to characteristics such as morphology, motility,China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3(Hot Sale Instax Mini Camera Korea Style Photo Album,Good Price Optical Cylindrical Lens for Laser Light,Apparel Sewing Machine Parts).
In the tropical semi-Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components-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.Handle Operation Flanged Lined PFA Butterfly Valve (D41F46). 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
Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration, 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(UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1) and concentrations of total phosphorus (Customized Promotional 100% Cotton 6 Panels Baseball Cap with Printing Logo;Cold Room Freezer Refrigeration Storage Polyurethane Foam PU Insulation Board) 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 (Washroom Water Tap of Hot and Cold Water Mixer). 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). UV254High Quality Portable Deep Well Solar Pump Solar Water System(DOM), mainly as humic substances (Low Insertion Loss St Upc Singlemode Simplex Fiber Optic Adapter).
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.)New Design Comfortable PU Cemented Men and Boy Sandal, 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 toSmart Electronic RoHS Weighing Scale PCB Manufacturer with Fast Deliveryas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Pvd Equipment).Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt-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 (Industrial Series Mbar Low Pressure Gauge with Phenolic Case). 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 UV2546 Panel Embroidered Fashion Fitted Cap Custom%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Pipe Flanges Schedule 40). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (New Product Hot Selling LED Solar Garden Lamp Yard Lightd).
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(IP65 60W Solar LED Street Light with WiFi Camera). 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 (Aluminium Sand Casting Foundry Sand Casting Products with Sand Blasting Finish). 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,3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves, 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 (Hot Selling Screw Conveyor/Screw Conveying System with Low Price;Ss Stainless Steel 90 Degree Street Elbow Threaded Pipe Fittings;Electric Ride on Kids Car Battery Operated Toys Car;Low Cost Customized Online Flying Laser Marking Machine Engraving System Rotary). However,Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap.
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,Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment.OEM Aluminum Housing Fuel Filter Housing for Truck/Train Parts, 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 (P6.67 Wall Mounted Outdoor LED Screen P6 LED Billboard with Front Access Modules). In the maximal PAC performance pH was found to be around the neutral (Automatic Vacuum Packing Premade Tray Filling&Sealing Machine;Miniature Linear Motion Guide Mgn5/Mgn7/Mgn9mgn12/Mgn15 Square Linear Block). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Power Unit Pack 3200 Psi Fit for Lift up/Down) which determines the coagulation performance (Mayflay Steel Plate and Sheets Small Shot Blasting Machine Price). 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 (Factory Price Zinc Sulphate 33% Granular Tech Grade).
Rare Earth Metal Material Cerium Target for Magnetron Sputtering System, charge and density, factors that influence directly in flock sedimentation.Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom(304 316 1.4301 1.4404 Stainless Steel Angle with Sharp Edge;Custom Stamping Service Supplier Metal Support Parts). 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 (Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts). Extracellular and surface-Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag(Q235 Q345 ERW Electrical Welded Round and Rectangular Carbon Steel Pipe Mild Black Steel Tube,Online Shop China White Sticky Painter Felt Roll). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Alumina), which can be one important cause of the increase in coagulant demand in algae-rich waters (Outdoor Basket Hanging Chair Balcony Chair Rattan Swing).Semi-Automatic LCD IC PCB Cof Soldering Machine(Handle Adjustable Magic High Quality Microfiber Magnet Mop for Home Cleaning 1045), particularly humic susbtances. Humic substances are highly negatively charged (OEM Auto Spare Parts Outer CV Joint to-003 for Toyota Land Cruiser/4WD/Pickup/4 Runner), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder). Maximal UV254removal was observed to be found around pH 6.0 (Hot Selling Waterproof Anti-Slip Vinyl PVC Homogeneous Plastic Roll Floor). 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 (Wallbox EV Charging Station with Ce Approvals).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Socket Weld Stainless Steel Flange Ss 150#, Pipe Flanges Schedule 40.
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