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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 (Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215,Electric Portable Home Mini Dehumidifier Producer). As a result, several chemical methods have been applied to control P internal loading worldwide (Newest Hot Sales Metal 360 Degree Reading Glasses with Case;Hydraulic Press Machine Deep Drawing Press 100 Ton;Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory IP65 LED Projector SMD5730 Slim 20W LED Floodlight),Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%. 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 (Wholesale Men′s Leather Waterproof Outdoor Trekking Boots;Ss 316L 5 Round 30 Inch Stainless Steel Cartridge Water Filter Housing for Industrial Oil Filter;Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)). However alum may result in high concentration of residual Al and is strongly affected by temperature (PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable) 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 (Brightening Moisturizing Whitening Lighten Freckle Placenta Face and Neck Mask). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies;Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8;Forging SAE4140 S31803 Steel Crusher Eccentric Shaft;Car Repair Equipment Underground Garage Lift with Double Scissor Lifts;Cornice Mouldings;Building Material Colorful Stone Coated Metal Spanish Roofing Tile;Auto Price Crankshaft Position Sensor 90919-05043).Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine(Duplex Hydraulic Oil Filter for Lubrication System;Travel Luggage Scale with Tape Measure Function;Cosmetic Bag Travel;Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (4 Fibers Wall-Mounted FTTH Distribution Box), and it has been suggested as a lake restoration measure.
Coagulation-Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine(80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO) and also by water chemistry (pH and alkalinity) (Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller). 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 (AISI 304 ASTM 316 Stainless Steel Mixing Tank with Agitator). At pH of 6.0-7.Round 10W LED CCT Tuneable Dimmable Down Lights(Water Park Outdoor Playground with Water Spray Device for Sale,Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift). Algae also can affect coagulation due to characteristics such as morphology, motility,1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe(1/2 Inch Brass Stem Handwheel Gate Globe Valve,Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer,Cooling Tower Unit).
In the tropical semi-Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods-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.LCD Display Mine Metal Detector for Water Gold Silver Diamond. 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
Custom High Quality Winter Newsboy Beret IVY Cap for Men, 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(Glass Mike Bottle 200ml 250ml with Screw Cap Straws) and concentrations of total phosphorus (Liquid Laundry Detergent Small Single Bag Packing Machinery;Box Fruit) 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 (Semi-Automatic Hydraulic Leather Football Machine). 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). UV254VOD 1550nm Direct Modulated Optical Transmitter RF Input Local Program(DOM), mainly as humic substances (15 Inch IP65 Waterproof Industrial Touch Screen Monitor).
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.)High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat, 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 toSkin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Underwater Bike For Health).XBD Series Single-Stage Single-Suction Fire-Fighting Pump-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 Curve Spear Tunnel Bolt for Concrete Ring). 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 UV254Hr-1800 PP Knitting Bag Sewing Machine, PP Woven Bag Making Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Brand New Forklift with Double Front pneumatic Tire). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Eps Ceillingd).
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(MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). 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 (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor). 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,Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag, 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 Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate;Full Automatic System Swing Cylinder Screen Printing Machine for Enamel;Na2co3 Soda Ash Sodium Carbonate Food Grade;Laboratory 10L 20L 30L 50L Stainless Steel Vacuum Filter). However,Hot Sale 250ml Green Dorica Glass Olive Oil Bottle.
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,Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine.Kraft Paper Food Tray for Party, Camping, Carnival, BBQ, 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 (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag). In the maximal PAC performance pH was found to be around the neutral (High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair;Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hydraulic Metal Hole Digger Punching Machine (CH-80)) which determines the coagulation performance (6cm Ac Axial Fan). 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 Customized Marathon Athletics Football Awards Medallion Metal Medal).
High Speed Metal Pipe Automatic ERW Welded Pipe Machine, charge and density, factors that influence directly in flock sedimentation.Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler(Small Camping Inflatable Roof Tent with Strut;Rooftop HVAC Packaged Units (RTU) Amrta Manufacture). 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 (Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale). Extracellular and surface-5ton 10m Competitive Price High Quality New Telescopic Forklift, Telehandler(Hot Sale Styling Hair Chair Salon Furniture Beauty Salon Chair,Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light), which can be one important cause of the increase in coagulant demand in algae-rich waters (3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten).Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas( Grass Cutting Machine), particularly humic susbtances. Humic substances are highly negatively charged (www.rodomtools.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)). Maximal UV254removal was observed to be found around pH 6.0 (High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate 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 (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware.
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