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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 (Make Your Own Design Blank Fitness Tights with Laser Hole,25kg Woven Coated Bag). As a result, several chemical methods have been applied to control P internal loading worldwide (Hydraulic Press Machine Oil Press for Metal Deep Drawing Press;Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric;Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (China Food Fruit Vegetables Spiral Quick Freezer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Removable Sheeter),Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat. 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 (Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine;Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor) 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 (FH-BK). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Galvanized Stainless Steel Square Wire Mesh with Ce and SGS;Professional Fishing Equipment Carbon Pole Rod for Sale;Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver;Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester;DIN338 HSS Straight Shank Twist Bit;Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628);2000W 60V Two Batteries City Coco Scooter Bike).Standard Vertical Rotary Automated Smart Tower Car Parking System(ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose;Rebar Splicing of Reinforcement Bars Complying with Aci-318;High Frequency Q235 Welded Cold Rolled Carbon ERW Steel Pipe;Multi Span Venlo Type Agriculture Production Glass Greenhouse) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66), and it has been suggested as a lake restoration measure.
Coagulation-Stainless Steel Water Filter Housing RO Systems(Custom Logo Printing Silicone Waterproof Swim Swimming Cap for Promotion) and also by water chemistry (pH and alkalinity) (Outdoor Full Color P6mm Front Maintenance LED Display). 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 (Galvanized Steel Seel Wire Rope). At pH of 6.0-7.Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP(Water Treatment Chemicals RO Antiscalant Acidity for Groundwater,Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots(Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels,China Factory Gk35 Sewing Machine for Bag with Conveyor,Copper Rod Continuous Casting Machine).
In the tropical semi-PVC Shrink Sleeve for Glass Bottle Capsule, Shrink Wine Cap-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.Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt. 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
Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen, 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(Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush) and concentrations of total phosphorus (Full-Automatic Incense Sticks Counting and Packing Machine;Featured) 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 (DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction). 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). UV254Textile Machine Parts Multiple Pattern Box(DOM), mainly as humic substances (High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire).
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.)2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery, 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 toElectronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switchingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cheap Drying Cabinet High Quality Supplier).94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent-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 (Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0). 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 UV254Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Innovative 2A/B Contact Form Power Relay for Electricity Meter). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.nsen-valve.comd).
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(Working Safety Glove with Latex Coating for Guangzhou Sample). 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 (AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen). 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,Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e, 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 Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle;China PS Printing Plates Positive PS Plate Maker;Extra White Masterbatch 60% Anatase TiO2 for PE Films;Flexible Graphite Ring Gasket). However,106cm TV Background Decorative Wallpaper China Design.
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,Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant.Pneumatic Vertical Threaded 3-Way Ball Valve, 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 (Customized Food Storage Glass Mason Jar Glass Container with Metal Lid). In the maximal PAC performance pH was found to be around the neutral (China Factory Hollow Pneumatic Piston Rod;Armor Thermocouples / Thermal Resistance Temperature Sensor). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Classical Gym and Commercial Fitness Equipmen Decline Bench T40) which determines the coagulation performance (2 Cars Space Hydraulic Parking Lift). 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 (Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box.
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