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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 (Rainbow Colorful Glitter Printing Custom Grosgrain Ribbon for Cloth,gilardinoflooring.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Home Decorative Universal Electric Fireplace with Remote Control and LED Flame;Factory Manufacture Clear and Brown BOPP Packaging Tape;Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale Custom Logo Printed Chocolate Candy Box). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Steel Fat 29er Mountain Bike),2017 New Material Fashion Luggage Good Suitcase. 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 (Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil;Textile Screen Printing Mesh Polyester Material;High Precise Process Custom Metal Works Services Sheet Metal Fabrication). However alum may result in high concentration of residual Al and is strongly affected by temperature (Pictures Printing A5 Document Pouches with Slide Zipper) 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 (Rfid Uhf Cards). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Vci Antirust Paper for Industrial Storage/Packaging;SKF Bearing;Precision CNC Turning Milling Machine Part for Auto Equipment;Small Portable Hand Cotton Picking Machine in India China Picking Cotton Machine;5 Square Manhole Cover; G-Sensor;Wholesale Price Ce RoHS Promotional Ultrasonic Humidifier Aromatherapy Diffuser).Stainless Steel SS304 and SS316 Closed Body Turnbuckle(Heated Lunch Box/ Food Insulation Plastic Box/Heat Preservation Plastic Box;Epoxy Resin Impregnated Fiberglass Binding Tape;www.vendingmachinechina.net;3D Skin Test Device for Skin Loosen/Pigmentation/Pore/Wrinkle/Moisture Content) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Digital Inkjet Large Format Flatbed UV Printing Ink), and it has been suggested as a lake restoration measure.
Coagulation-Electric Hand Circular Saw for Wood Cutting 185mm(19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU) and also by water chemistry (pH and alkalinity) (430 Hot Rolled Stainless Steel Coil No. 1 Finish). 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 (Women Customized Round Neck Long Sleeve Sweater Fashion Clothes (19-335)). At pH of 6.0-7.Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66)(High Quality Industrial Grade Anhydrous Sodium Sulfate,Custom Logo Small Beer Mug One Ounce Mini Stein Glass). Algae also can affect coagulation due to characteristics such as morphology, motility,Alternator for Toyota 91, 92 Mr2, 100211-6110, 27060-74180, 2706074180, 1002116110(Certified Factory 304 Stainless Steel Corrugated Flexible Yellow Natural Gas Hose,Empty Toner Lotion Pump Glass Bottle Cosmetic Bottles,Machine To Make Hydraulic Hoses).
In the tropical semi-Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory)-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.16mm Rotary Potentiometer with Switch for Audio Equipment. 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
Food Processing Industry Fruit Vegetable Drying Machine, 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(Best Price 3D PVC Wall Panels Colored for Decorative and Art) and concentrations of total phosphorus (Diesel Engine Mobile Rotary Screw Scroll High Pressure Air Compressor;m.doingshoes.com) 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 (201 Stainless Steel Coil /Stainless Steel Sheet /Stainless Steel Plate). 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). UV254Hot Sale Bamboo Toothbrush in Flate Simple Design(DOM), mainly as humic substances (Transformer Silical Gel Breather DIN -42567 Form C).
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.)L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906), 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 toAntitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Labelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fitness Gym Leggings).Virtual Reality Egg Game Machine Amusement Riding Machine for Sale-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 (Building Material Stone Tile Full Body Marble Porcelain Tile). 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 UV2547, 5kw Electric Conversion Kits for Light Car/Van/Truck%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( 5.0mm Disk). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Ambulatory Blood Pressure Monitord).
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(Push up Breast Enlargement Bra SGS Test Certificate Backless Adhesive Silicone Bra Transparent). 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 (Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts). 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,Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller, 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 (Ss Wire Mesh Heat Resistant Wire Mesh Conveyor Belt;Cosmetic Raw Materials 3-O-Ethyl Ascorbyl Ether Powder CAS 86404-04-8;Hot New Kids Machine High Quality Self-Control Cat Mechanical Parts Swing Carnival Rides for Sale;0.2dB LC Quad Fiber Optic Adaptor with Flange Without Flange). However,Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic.
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,Waste Pet Plastic Bottle Crushing Washing Recycling Machine.12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery, 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 (W/B Block-out Fabric Sublimation Textiles for Backdrop with Black Coating). In the maximal PAC performance pH was found to be around the neutral (OEM High Efficiency Polycrystalline 260W Solar Panel;High Quality of Glassware Bottle of Essential Oil Reed Diffuser Perfume). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet) which determines the coagulation performance (Beautiful Smile Dental Tooth Whitening Kit with Mini LED Light). 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 (36W/48W Interchangeable AC DC Adapter Free Samples 14 Years Experience).
Outdoor LED Courtyard Solar Street Lights for Garden Path Road, charge and density, factors that influence directly in flock sedimentation.Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate(Durable Building Construction 3 Ton Hoisting Electric Winch for Sale;Renewable Biodegradable Stand up Pouch Coffee Manufacturer in China). 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 (PVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rolls). Extracellular and surface-Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250(Automatic Chemical Dosing System Equipment,NEMA 17 0.9/1.8 Degree Two Phase Electric Step Stepper Motor with Permanent Magnet Brake). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Promotion 100%Cotton Baseball Cap Manufacturer Export to Europe), which can be one important cause of the increase in coagulant demand in algae-rich waters (Auto Parts Nitril Rubber Bellows with Competitive Price).Manufacture Antique Hydraulic Electric Base Vintage Barber Chair(Fused Silica Flange with High Temperature Resistance), particularly humic susbtances. Humic substances are highly negatively charged (cute dog harness pet), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Brake Light Rear View Camera for Fiat Ducato). Maximal UV254removal was observed to be found around pH 6.0 (Js500 Twin-Shaft Concrete Mixer for Block Machine). 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 (China Construction Machinery Sheet Metal Parts Manufacturers CNC Auto Parts).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing.
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