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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 (Breathable Pet Dog Shoes with Reflective Magic Tape Straps,Special Bending Wire Forming Spring). As a result, several chemical methods have been applied to control P internal loading worldwide (2018 Newest 12inch Music Sound Box for Computer;Customized Cutting Tool Solid Carbide Tool Taps (TS-100002);Cyclone Mesh Turbo Diamond Saw Blade for Ceramic Tile). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (16800mAh 800A Car Emergency Battery Booster Portable Jump Starter). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,106cm TV Background Decorative Wallpaper China Design, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (WiFi Mini Security Remote Monitor Camera Wide Angle HD 1080P Motion Detect IR Night Vision H. 264),Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant. 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 (Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable;Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle;High Quality Antibiotics Powder Enrofloxacin CAS 93106-60-6). However alum may result in high concentration of residual Al and is strongly affected by temperature (Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller) 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 (Explosion-Proof Conduit Body Box Lb Type). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (RFID and Remote Controller Small Electronic Lock with Password;OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication;Biodegradable Packaging Small Plastic Compartment Storage Box for Food;Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing;35tons Semi Auto Vertical Plastic Injection Machine Make Electric Plug;Electrically Heat Furnace Prime Quality Radiant Tubes;Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window).Pneumatic Vertical Threaded 3-Way Ball Valve(Colored Corrugated Steel Roofing Sheet with ISO9001;Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8);Black Pvc Cable Trunking;Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (FRP Fiberglass Underground Septic Tank for Effluent Treatment), and it has been suggested as a lake restoration measure.
Coagulation-Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality(96 Pin IDC Cable Connector D-SUB Connector SCSI Type) and also by water chemistry (pH and alkalinity) (Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse). 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 (Aluminum Honeycomb Panel For Boat Building). At pH of 6.0-7.Pedstal Electric Stand Fan 5 Speed Control Air Cooler(OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated,Steel Jacket Steam Insulation Pipeline Production Best Quality). Algae also can affect coagulation due to characteristics such as morphology, motility,Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration(Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting,2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter,Kitchen Gadget Stainless Steel Pizza Knife/Circular Roller Pie Cutter).
In the tropical semi-Custom Ductile Iron Casting Parts Gray Iron Sand Casting-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.Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box. 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
Precision Machining Components for Hydraulic Cylinder Producing, 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(Smelting Furnace Dust Collector Fiberglass Bag Filter) and concentrations of total phosphorus (China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop;Tianyu Metal Door Frame Cold Roll Forming Machine) 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 (European VDE Schuko 3-Pin Waterproof IP44 Power Plug). 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). UV254One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit(DOM), mainly as humic substances (Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress).
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.)Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware, 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 toEco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrushas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester).Full Car Key for Chrysler 5+1 Button Remote Control-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 (Custom Hardware Lathe Turning Steel Metal Parts High Precision CNC Machinery/Machined/Machining). 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 UV254WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.suase-plastic-mould.comd).
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(Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle). 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 (White Chemical Coating Powder for Fast Dry Sublimation Paper). 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,Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453), 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 (Nyp Rotor Type Oil Pump High Viscosity Internal Gear;BPW Spring Mechanical Steel Oil Fuel Diesel Tank Semi Trailer for Sale;Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132);Anvil Air Compressor Supplier). However,Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel.
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,NEMA IP65 Wall Mount Electric Metal Cabinets.11mm Neck Crimp Cap Vials with Patch, Cap Septem, 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 (Licensed Mercedes-Benz Gtr 2 Seats Children Car in Black). In the maximal PAC performance pH was found to be around the neutral (OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat;Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (20qt Portable Small Rotomolded Insulated Medical Cooler Box) which determines the coagulation performance (100kw AC Three Phase Silent Portable Electric Diesel Generator). 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 (Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener).
Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797), charge and density, factors that influence directly in flock sedimentation.Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts(1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe;Quick Charger 18W USB-C Pd Charger for iPhone11). 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 (75 Inch LCD Smart Interactive Whiteboard Touch Screen with 4K Screen Display). Extracellular and surface-10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment(Dental Bottom-Loading Furnace Intelligent Vacuum Porcelain Furnace Zirconia Sintering,Carboxy Methyl Cellulose (CMC) for Daily Use). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Fng Fgg 0b 2 3 4 5 6 7 9pins High Quality Circular Cable Connector with Release Yard), which can be one important cause of the increase in coagulant demand in algae-rich waters (Outdoor LED Courtyard Solar Street Lights for Garden Path Road).Solid Surface Grade Grinding Alumina Tyihydrate(Equipment Auto Fire Extinguisher Ball Automatic Fire Extinguisher Ball), particularly humic susbtances. Humic substances are highly negatively charged (Gold Hyaluron Pen Needle Free Hyaluronic Injection Lip Lifting Wrinkle Removal), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Black Matt Strong Metal Bag Slider Zip Pullers). Maximal UV254removal was observed to be found around pH 6.0 (3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves). 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 (1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable.
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