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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 ( Water,Steel Pneumatic Automatic Car Chassis Number DOT Peen Marking Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Ring Die Sawdust Wood Pellet Making Machine Line;Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine;Prime SPCC Electrolytic Tin Plate for Making Cans). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Large Size 300mm Low Noise 55dB IP44 Air Blower for Public Places). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best 1.75mm 3mm ABS PLA 3D Printer Filament Supplier 1kg 5kg for 3D Printing Clear ABS Filament, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Bag Making Material Woven Suppliers for Sale),China Wholesale Hot Sale Microfiber Car Cleaning Towel. 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 (Microfiber Wiping Lens Cleaning Cloth for Glasses;Double Layer Waterproof and Durable Asphalt Shingle Roof Tile Roofing Shingles;2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment) 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 (Resort Tent Dome). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale; Disc-Chain Automatic Feeding System;20% White Vinegar Available for Agricultural or Cleaning Purposes;Dart Extrusion Machinery Making Twin Screw Extruder;Professional Anti-Slip Trampoline Socks for Trampoline Park with Different Sizes;100% Fabric Advertising Display See Through Mesh Banner Windproof;ATV Electric Winch with 3500lb Pulling Capacity (Star Model)).530ml Glass Drinking Water Bottle with Silicone Sleeve&Handle Lid(1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump;ISO SGS Certified 100% Natural Spirulina Powder;Customized Metal Casting Mechanical Machine Parts with Powder Coating;55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector), and it has been suggested as a lake restoration measure.
Coagulation-Cylinder Borosilicate Glass Cooking Oil Bottle with Spout(Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball) and also by water chemistry (pH and alkalinity) (Disposable Take out Paper Food Salad Sushi Lunch Box Container). 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 (Tungsten Tig Welding Rod). At pH of 6.0-7.11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte)(99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering,High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Selling SAA Rcm Listed CCT Changeable LED Down Light(Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line,Drawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapes,cnzxpump).
In the tropical semi-Ferrous Sulphate Heptahydrate for Water Treatment-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.Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair. 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
NF3, Nitrogen Trifluoride, Liquid Gas, 99.99~99.999%, 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(Eco-Friendly Natural Organic Bamboo Toothbrush) and concentrations of total phosphorus (Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite;3000g/Sq. M Thick Industrial Oil Aborbent Cotton Felt Sheets) 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 (China Metal Cooling Fan for Dry-Type Transformer). 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). UV254Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring(DOM), mainly as humic substances (Superior Fabric Core Conveyor Belts Vulcanizing Press From China).
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.)Colorful Commercial PVC Vinyl Flooring for Office, 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 toTempered/Toughened Glass/Window/Shower Door Float Glass (T-TP)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Electric Ice Block Crusher Machine for Restaurant).Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades-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 (1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar). 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 UV254Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Yvf2 Frequency-Variable Speed-Regulation Inverter Motord).
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(Hydrochloric Acid (HCl) ). 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 (Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover). 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,Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack, 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 (Manufutuer Promotes Skin Regeneration Repair Anti Aging Smoothing Fine Lines Facial Mask;Portable Animal High Frequency X Radiography Machine (HP-HFX600V);Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold;Air Compressor Pump Head). However,Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring.
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,Seamless Circular/Square/Rectangular Steel Tube.Construction Equipment 1.5 Cube Materials Portable Concrete Mixer, 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 (Cement Bag Manufacturer Kraft Paper Valve Bag for Cement). In the maximal PAC performance pH was found to be around the neutral (Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling;Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (PC260 3.0-24V 24*27mm 3W DC Motor for Electric Garden Tool) which determines the coagulation performance (Fashion Jewellry 925 Sterling Silver or Brass Adjustable Bracelets for Girls). 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 (LED Dancing Wing Props Halloween Christmas Party Supplies).
Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler, charge and density, factors that influence directly in flock sedimentation.Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing(Glass Shower Door Frame Waterproof Seal PVC Seal;2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter). 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 (Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel). Extracellular and surface-Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch(cnmirant,12mm Multiwall Green Perforated Hollow Polycarbonate Sheet). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Best Quality Tianeptine Acid / Tianeptine CAS 66981-73-5), which can be one important cause of the increase in coagulant demand in algae-rich waters (Chiller Price Water Cooling System Screw Air Cooled).2018 Hot Selling Gold Stainless Steel High Bar Chair(1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD), particularly humic susbtances. Humic substances are highly negatively charged (4lz-4.5 Small Grain Tank Manual Operation Rice Combine Harvester), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( NdFeB Magnet for Motor (N38H)). Maximal UV254removal was observed to be found around pH 6.0 (15kg Big Payload Unmanned Aerial Vehicle (uav) with Various Camera Payload Optional). 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 (2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Precision Ultrasonic Vibro Screen for Refractory Material Separating.
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