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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 (Plastic Fork Mould for Cake Disposable Tableware Injection Molding,Factory Sell Outdoor 4MP Poe Dome IP Camera). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6;Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment;HR/CR/GI High Frequency Longitudinal Seam Tube Mill). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Portable Basketball Goal with Removable HDPE Base Adjustable Backboard Spring Rim for Kids),Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display. 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 (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). However alum may result in high concentration of residual Al and is strongly affected by temperature (Full Car Key for Chrysler 5+1 Button Remote Control) 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 (Ear Loop Face Mask). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects;ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt;High Quality Korea Standard Door Core Material LVL;Hight Quality Air Filter C1250 for Mann and Atlas Air Compress;Large Pillar Candles For Fireplace;Cut and Impact Resistant Hand Protection Glove;Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System).60 Grit Mini Abrasive Flap Disc for Carbon Steels(Self-Adhesive Non-Slip Sticky White Felt for Easy Painter; Round Jaws Lock Wrench Wr Type;HDPE Double Wall Corrugated Polyethylene Storm Sewer Pipe Manufacturers;Double Screws Textured Soy Protein Artificial Meat Tvp Tsp Extruder) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution), and it has been suggested as a lake restoration measure.
Coagulation-High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects(Large 25X100m Exhibition 2500 Seat Tent for Trade Show) and also by water chemistry (pH and alkalinity) (Custom Made Round Shape Cardboard Dry Fruit Gift Paper Box). 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 (OEM Stainless Steel Precision Casting Door Lock Cylinder). At pH of 6.0-7.Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm(Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter,Cheap Spring Bonnell Inner Spring for Bedroom Mattress). Algae also can affect coagulation due to characteristics such as morphology, motility,(1.5/2/2.5 /3/4/12 inch) Aluminium Hot Dipped Square Galvanized Pipe for Equipment Machine(Huayao Smart Pdlc Film/Magic Dimming Intelligent Film for Glass Lamination,Programmable Ozone Aging Test Equipment for Rubber Cable Resistance,50.8mm Focal Length Laser Focus Lens Factory OEM/ODM Products).
In the tropical semi-Polypropylene Strapping Band Production Line/PP Strap Making Machine-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.Quotation Two Panel Outdoor Jungle Gym Rope Climbing Plastic Structure for Amusement Park. 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
A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16, 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(Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt) and concentrations of total phosphorus (Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories;High Lumen Epistar 9W 10W 15W 20W 25W COB LED Chip) 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 (Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining). 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). UV254Small MOQ Food Grade Glass Bottle Wine Cork Stopper(DOM), mainly as humic substances (Wholesale 100% Cotton Luxury Hotel Bath Towel Set).
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.)Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line, 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 toCustom Own Shoes Bag Garment Brand Logo PVC Rubber Label/PVC Patch/Accessories for Clothas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Auto Radar Detectors).Nylon Watch Bands with Metal Buckle 20mm Strap-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 (Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine). 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 UV254400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Clear Acrylic Chinese Tea Table (BTR-Q1012)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Engraving Jewelry Machined).
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(High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line). 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 (High Quality C5/C3 Grinding Ball Screw From Taiwan). 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,Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators, 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 (CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router;Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W;China Label Screen Printing Machine Suppliers;4x8 Laser Cutter). However,10m3 Mobile LPG Filling Skid Station for Gas Cylinders.
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,Printing Paper Coated Art Paper C2s/C1s Gloss/Matt Art Printing Paper.Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter, 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 ( Water). In the maximal PAC performance pH was found to be around the neutral (Ring Die Sawdust Wood Pellet Making Machine Line;Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Prime SPCC Electrolytic Tin Plate for Making Cans) which determines the coagulation performance (m.sunhingstones.com). 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 (Large Size 300mm Low Noise 55dB IP44 Air Blower for Public Places).
2-7dBi GPS/GSM SMA RF Coaxial High Gain WiFi Antenna, charge and density, factors that influence directly in flock sedimentation.Company From China, Made in China Superior Black T Bolt(Microfiber Wiping Lens Cleaning Cloth for Glasses;Double Layer Waterproof and Durable Asphalt Shingle Roof Tile Roofing Shingles). 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 (2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)). Extracellular and surface-Carbon Steel Carry Idler Belt Conveyor Guide Roller(Front Module,Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Disc-Chain Automatic Feeding System).Cement Roofing Sheets Pigment Yellow Iron Oxide Prices(20% White Vinegar Available for Agricultural or Cleaning Purposes), particularly humic susbtances. Humic substances are highly negatively charged (Christmas Decoration Inflatable Santa Claus Christmas Cartoon), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Dart Extrusion Machinery Making Twin Screw Extruder). Maximal UV254removal was observed to be found around pH 6.0 (100% Fabric Advertising Display See Through Mesh Banner Windproof). 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 (ATV Electric Winch with 3500lb Pulling Capacity (Star Model)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Carbon Fiber Composite Autoclave Pressure Vessel for Sale.
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