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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 (1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire,Laser For Facial Hair Removal). As a result, several chemical methods have been applied to control P internal loading worldwide (China Supplier Good Quality Bending U Bolts Parts;OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag;Automatic Control Apricot Shell Charcoal Carbonization Kiln Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (304L 316L Stainless Steel Sheets From Ticso). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Automatic Column and Boom Welding Manipulator Dlh, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (prestigelaminatefloor),3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material. 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 (Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices;Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove;750ml Round Shape Beer Wine Liquor Glass Bottle High Quality). However alum may result in high concentration of residual Al and is strongly affected by temperature (M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher) 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 (Remote Control Sockets). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (6 Head Garment Computerized Embroidery Machine Industrial Use for Sale;Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale;4-Way Brass Angle Valves Chrome Plated Water Supply Stop;Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps;High Quality 1000kg Small Rice Mill Machine;Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith;Wallbox Socket Type 2 16A 3.7kw Single Phase EV Charging Point EV Charger for Electricvehicles).Auto Parts for Plastic Products Injection Mould Mold Tooling(Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton;Rice Cracker Core Filling Snacks Food Making Machinery;Butterfly Valve With Positioner Factory OEM/ODM Products;Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Speed 110V-220V 60X60X25mm Axial Brushless Cooling AC Ec Powerful Fan), and it has been suggested as a lake restoration measure.
Coagulation-2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids(2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer Machine) and also by water chemistry (pH and alkalinity) (Home Security PRO Hunter RF Signal Detector Detect Bugging Devices in Your Home). 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 (China Factory Brass Pipe Fitting). At pH of 6.0-7.Automotive Aluminum Engine Parts Low Pressure Casting(Frozen Food,Good Quality R134A Refrigerant Copper Tube Fin Heat Exchanger). Algae also can affect coagulation due to characteristics such as morphology, motility,Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose(Customized Plastic Injection Mould Products Industrial Parts Plastic Cross Pipe,High Pressure Rubber Hydraulic Hose Assembly,Safety Face Shield).
In the tropical semi-Public Address System High Power Range Outdoor Column Speaker, FCL-440-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.Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games. 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
New Product 2019 Milky White Electrochromic Smart Film, 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(Triangle Plastic Checkout Counter Divider Bar with Logo Printed) and concentrations of total phosphorus (Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking;Zinc Coating Bending Stamping Sheet Metal Fabrication Machine Part) 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 C3 C5 Ground Miniature Ball Screw 0802). 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). UV254Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp(DOM), mainly as humic substances (Log Debarker Veneer Rotary Peeling Machine).
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.)Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047), 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 toFoshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.gaofeng-petro.com).Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor-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 ( 12V- 48V DC). 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 UV254Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Productsd).
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(OEM Manufacturer 6 Rolls Shrink Pack BOPP Crystal Tape). 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 (Ocs-Y 10 T 20 Ton Crane Scale Load Cell 10000 Kg Crane Scale). 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,Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate, 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 (Factory Supply Cold Rolled Stainless Steel Coil Price;Self Leveling Flow Mortars Additives Vae Redispersible Polymer Powder;2019 Mini I9/I9s Tws Stereo Wireless Headphones Blue Tooth Sport Earphone Earbuds;Nose Face Mask). However,Living Room Furniture TV Stand Electric Fireplace with No Heating.
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,High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings.15 Inch IP65 Waterproof Industrial Touch Screen Monitor, 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 (All-in-One Fool Metal Continuous Casting Machine/Complete CCM with Very Low Investment). In the maximal PAC performance pH was found to be around the neutral (Building Material 80X160cm Glazed Polished Porcelain Natural Stone Flooring Full Body Marble Tile;2019 New Designed High Quality Playground Indoor Kids′ Plastic Slide). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (JIS G3441 Machining and Structure Alloy Steel Pipe) which determines the coagulation performance (Waterproof Foldable Baby Bed Mum Crib Infanette Pilch Snoopy Diaper Case Bag (CY3290)). 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 (Girls Unicorn Costume Party Dress Tutu Kids Cute Flower Princess Pageant Carnival Clothes).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar.
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