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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 (PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material,Stainless Steel Chemical Heating Jacketed Cooling Mixing Agitator Slurry Tank). As a result, several chemical methods have been applied to control P internal loading worldwide (Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle;White Chemical Coating Powder for Fast Dry Sublimation Paper;Trenchless Directional Tricone Drill HDD Reamer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (AISI 304 316L 309S 317L 321 904L 421 Stainless Steel Strip). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Thin Nozzle Tube for Piston Cooling Cylinder Chamber, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Tork Led Twist Lock Photocell Supplier & Factory),Farm Equipment Feed Storage Grain Feed Silos for Sale. 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 (Nyp Rotor Type Oil Pump High Viscosity Internal Gear;BPW Spring Mechanical Steel Oil Fuel Diesel Tank Semi Trailer for Sale;Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Licensed Mercedes-Benz Gtr 2 Seats Children Car in Black) 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 (Big Smart Hydroponic Planter All in One Hydroponics). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat;Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085);20qt Portable Small Rotomolded Insulated Medical Cooler Box;Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener;Adjustable Freestyle Urban Slalom Skate for Kids with CNC Chasis (JFSK-100-1);1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe;Quick Charger 18W USB-C Pd Charger for iPhone11).Building Material Stone Tile Full Body Marble Porcelain Tile(75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display;Carboxy Methyl Cellulose (CMC) for Daily Use;Cnc Machine For Sculpture;Fng Fgg 0b 2 3 4 5 6 7 9pins High Quality Circular Cable Connector with Release Yard) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Outdoor LED Courtyard Solar Street Lights for Garden Path Road), and it has been suggested as a lake restoration measure.
Coagulation-Cosmetic Raw Materials 3-O-Ethyl Ascorbyl Ether Powder CAS 86404-04-8(Equipment Auto Fire Extinguisher Ball Automatic Fire Extinguisher Ball) and also by water chemistry (pH and alkalinity) (Black Matt Strong Metal Bag Slider Zip Pullers). 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 (Color Interlock Brick Machine). At pH of 6.0-7.Hot Sale Pig Farm Equipment Galvanized Farrowing Pens(3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves,1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire). Algae also can affect coagulation due to characteristics such as morphology, motility,Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs(China Supplier Good Quality Bending U Bolts Parts,OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag,Modern PP Seat Office Chair with Four Steel Leg Ow-J095).
In the tropical semi-Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse-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.Jy-616 Conference Plastic Auditorium Chairs with Cup Holder Cinema Seating. 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
Good Quality Tungsten Carbide Round Nose End Mill, 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(Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices) and concentrations of total phosphorus (Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove;Amazon Hot Sale Mini Glass Essential Oil Diffuser Bottle Refill) 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 (6 Head Garment Computerized Embroidery Machine Industrial Use for Sale). 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). UV254HPL Board Top Adjustable Coffee Dining Table(DOM), mainly as humic substances (Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale).
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.)IC ID Epoxy Tag Entrance Guard Card Key Fob for Elevator Property Management, 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 toWallbox Socket Type 2 16A 3.7kw Single Phase EV Charging Point EV Charger for Electricvehiclesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Brushless Dc Motor Bldc Motor 65 Type).Pig Farm Automatic Feeding System, Disc-Chain Automatic Feeding System-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 (Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water). 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 UV254Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Speed 110V-220V 60X60X25mm Axial Brushless Cooling AC Ec Powerful Fan). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Car License Plate Sublimation Aluminum Printing Sheets with Glossy Goldd).
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(Home Security PRO Hunter RF Signal Detector Detect Bugging Devices in Your Home). 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 (Frozen Food). 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,China OEM Cast Iron Tractor Farm Clutch Pulley, 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 (High Pressure Rubber Hydraulic Hose Assembly;China Wholesale Hot Sale Microfiber Car Cleaning Towel;9-80V Laser Red Zone LED Work Safety Lights for Forklift Truck;m.cixi-gts.com). However,China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China.
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,Cement Grout Pump Grouting Machine Price Concrete Grouting Machines.(Search enter) ISO13485 manafacturer for industry, surgical, medical disposable clothes, 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 (Triangle Plastic Checkout Counter Divider Bar with Logo Printed). In the maximal PAC performance pH was found to be around the neutral (Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking;Digital Control Gold Powder Coating Machine for Metals). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion) which determines the coagulation performance (Production Line Continuous Plastic Bag Batch Number Inkjet Printing Machine). 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 (Custom C3 C5 Ground Miniature Ball Screw 0802).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.China Supply MTP/APC Female to FC/APC Fanout Cable 12 Fibers Single Mode Patch Cord.
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