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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 (600tc Bamboo Cotton Bed Sheet Set Charcoal Color,Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015);LED Lighted Mirror with Bluetooth Functions;Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Supermarket for Cold Room Price Air Cooled Condenser Unit). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Readymade Contemporary Grey Tiny Compact Modern Ensuite Small Shower Room Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Embroidered Badge),Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture. 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 (Plastic Fork Mould for Cake Disposable Tableware Injection Molding;Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6;Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment). However alum may result in high concentration of residual Al and is strongly affected by temperature (HR/CR/GI High Frequency Longitudinal Seam Tube Mill) 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 (Recycling and Environmental Protection Kraft Paper Bag with Rope Handle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4);Small Scaled Laboratory Pharmaceutical Dry Mixing Machine;Outdoor High Pressure Isolating Vacuum Load Switch;Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale;Tire Intelligent Management Solution Tire temperature and pressure real-time monitoring&tire RFID automatic identification;Full Car Key for Chrysler 5+1 Button Remote Control;Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects).Industrial Automatic High Quality PVC Fast Speed Roller Shutter(ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt;High Quality Korea Standard Door Core Material LVL;Automatic Chemical Dosing System Equipment;Hight Quality Air Filter C1250 for Mann and Atlas Air Compress) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cut and Impact Resistant Hand Protection Glove), and it has been suggested as a lake restoration measure.
Coagulation-Bento Lunch Box, Meal Prep Containers, Reusable 3-Compartment Plastic Divided Food Storage(Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System) and also by water chemistry (pH and alkalinity) (Self-Adhesive Non-Slip Sticky White Felt for Easy Painter). 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 (Body Whitening Cream). At pH of 6.0-7.Custom C3 C5 Ground Miniature Ball Screw 0802( Round Jaws Lock Wrench Wr Type,Double Screws Textured Soy Protein Artificial Meat Tvp Tsp Extruder). Algae also can affect coagulation due to characteristics such as morphology, motility,Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding(High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution,Large 25X100m Exhibition 2500 Seat Tent for Trade Show,Dirt Catchers).
In the tropical semi-Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933-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.High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress. 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
Paint Spray Booth Air Flow Vehicle Paint Booth for Sale, 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(Cheap Spring Bonnell Inner Spring for Bedroom Mattress) and concentrations of total phosphorus (Huayao Smart Pdlc Film/Magic Dimming Intelligent Film for Glass Lamination;2019 New LED 25W Logo Projection Effect Light Bar Light Cafes Light Hotel Light KTV Light) 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 (Tuna Canned Shrimp Vannamei Butchery Cold Room Henningson Cold Storage Walk in Cold Room Price). 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). UV254High Purity Calcined Alumina Micro Powder for Ceramics Refractories(DOM), mainly as humic substances (Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt).
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.)Customized Dummy Animal Teething Toy Design Baby Pacifer, 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 toHeavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Miningas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Disc Type Toughened Glass Insulator for Distribution Transformer).Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings-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 (4X Laser Iridium Spark Plugs Pzfr6r 5758 for Audi A1 A3 VW Passat EOS Skoda Seat). 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 UV254Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1 Holder Mobile Electric Stainless Steel Plate Warmer Cart). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (1.4 Bdo Supplier Suppliers for Saled).
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(Gear Operated Cast Iron Wafer Type Butterfly Valve). 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 (Street Lighting 50W 100W 150W 200W LED Street Lamp Source Outdoor LED Street Light). 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,Automatic Concrete Paving Interlocking Block Brick Making Machine, 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 (Stainless Steel Electric Heating Mixing Kettle for Food Industry;High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line;High Quality C5/C3 Grinding Ball Screw From Taiwan;Ratchet Wrenches). However,Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows.
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,Plastic Injection Moulding for Plastic Car Toys Products, Truck Parts.Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly 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 (High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing). In the maximal PAC performance pH was found to be around the neutral (Manufacturer of Various Color Graduation Tassel Honor Cords;CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W) which determines the coagulation performance (Full Complement Cylindrical Roller Bearing F-553337.1 Excavator Cylindrical Roller Bearing). 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 (China Label Screen Printing Machine Suppliers).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars.
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