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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 (HVAC Connected Large Area Scent Diffusion System with 2 Bottle,3 Pin Male And Female Connector). As a result, several chemical methods have been applied to control P internal loading worldwide (Fashion Leather Wristband USB Disk 4GB to 32GB;Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag;Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Eco Brava Small Mud Interlock Brick Press Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Healong Fashion Sportswear Latest Design Blank Gym Sweatshirts Custom Cotton Hoody Sweatshirts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Pressure Laminating Lamination Single Opening Hot Press Machine),Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock. 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 (7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing;Textile Machine Parts Multiple Pattern Box;Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker). However alum may result in high concentration of residual Al and is strongly affected by temperature (Accept Customization Perfume Direct with Good Price) 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 Computer Glasses For Big Heads). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (AAC Autoclaved Aerated Concrete Brick Making Machine;Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter;Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette;FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound;Wholesale Decorative 3D Metal Channel Letters Sign;Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair;2400 Dpi Resolution Offline CTP Offset Printer).2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card(Trailer Part Coupling;Small MOQ Food Grade Glass Bottle Wine Cork Stopper;Video Camera 4k;High Quality Precision Plastic Mold/Mould Insert) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Alternator for Toyota 91), and it has been suggested as a lake restoration measure.
Coagulation-Flash Freezing Equipment Stainless Steel Freezer Blast Freezer Chiller Cabinet(Guard Rail Roll Forming Machine 2.0-4.0mm Thickness) and also by water chemistry (pH and alkalinity) (China Genuine Leather White Color Safety Shoes). 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 (Android Walkie Talkie Watch). At pH of 6.0-7.9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting(HS20-600 Shipping Lifting Device Customized Hydraulic Station,China Supplier Customized Polish Storage Wall Mounted Wine Rack). Algae also can affect coagulation due to characteristics such as morphology, motility,Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner(Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use,Zp9 Punches and Dies Rotary Tablet Press for USA Market,Paper Box Origami).
In the tropical semi-New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds-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.New Material of Coated and Veneered Wooden Grain Paper. 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
All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable, 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(Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863) and concentrations of total phosphorus (Gi Galvanized Iron Sheet Hot Dipped Galvanized Steel Sheet Galvanized Sheet Metal Plates;20kw Evi Air Source Heat Pump Water Air Source Heat Pump -25degree) 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 (Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag). 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). UV254Wholesale Foldable Desk Silicon Mobile Phone Stand(DOM), mainly as humic substances (Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor).
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.)300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131, 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 toIndustrial Aluminum Extrusion Profiles 6063 T5as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Manual Pressure Sustaining Control).Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle-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 (Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valve). 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 UV254American Double Hung Thermal Break Aluminum Window in China%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Patened Design Large Mich Indoor Trampoline Park for Kids). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Electric Platform Liftd).
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(TUV Standard China Jump Park Free Jumping Bounce Bed Trampoline Park for Kids). 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 (Hot Sale Glass Manual Salt Grinder Pepper Mills/Spice Jars). 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,Fashion Design Steel-Wood Large Conference Table, 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 (Rare Earth Metal Material Cerium Target for Magnetron Sputtering System;Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal;Disposable Rotatable Endoscopic Grasping Net Loop;Industrial A3 A4 Size Creaser Perforator Slitter Kiss-Cut Automatic Paper Folder Machine). However,Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck.
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,Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids.Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting, 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 (Composite Suspension Transmission Insulator String with Electrical Power Fitting). In the maximal PAC performance pH was found to be around the neutral (SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker;Aluminum DJ Truss for Exhibition Lighting Truss). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Biodegradable PLA Film for Food /Fruit Packaging) which determines the coagulation performance (Double Bowl Sink For Kitchen). 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 (Automatic Paver Block Making Machine for Sale).
OEM Custom Plastic Injection Mold for Mobile Phone Case, charge and density, factors that influence directly in flock sedimentation.China Manufacrure Mobile Asphalt Batch Mix Plant for Sale(12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage;Outdoor Body-Building Sitting Device for Improving Stability of Lower Limbs). 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 (Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop). Extracellular and surface-Synthetic Fiber Filter Rolls Filter Media for Air Conditioning(Plastic PVC/Pet Package Round Box with Paper Lid, Solar Water Pump for Garden Irrigation (SC Series)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Smart Label RFID UHF Sticker with Special Offer for Asset Tracking), which can be one important cause of the increase in coagulant demand in algae-rich waters (Painted Black Grade U3 Studless Boat Anchor Chain for Sale).1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine(2019 Hot Sale Solar Light String Tree Park Decoration Light), particularly humic susbtances. Humic substances are highly negatively charged (Candy Packing Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New Style Customized Ce Approved Adjustable Inline Skate (SS-179A-BW)). Maximal UV254removal was observed to be found around pH 6.0 (Throttle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruze). 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 (Professional Produce Dmp-430A Vacuum Tray Sealer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca.
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