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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 (Food Grade Oval Cute Newborn Pacifiers with Soft Soother,New Portable Prover Tank Measuring Can Used for Gasoline). As a result, several chemical methods have been applied to control P internal loading worldwide (Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump;Permanent Magnetic Separator for Conveyor Belts;High Quality HVAC Exhaust or Supply Plastic Air Valve). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Inch Roller Bearing),Women′s Mesh Contrast Pleat Fashion Black Tank Top. 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 (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit;Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Transmission Line Steel Monopole Steel Tower). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Camera) 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 (cnsdgt.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Industrial Air Cooled Heat Pump Water Chiller in Many Field;14kw Heating Capacity Evi Air to Water Heat Pump;1HP Floting Wheel Aerator;48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing;Eco-Friendly Supplier of High Quality WPC Fence Panel;Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set;Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board).Folding Pile Driver Machine with Hydraulic Power(P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen;Automatic High Speed Welding Manipulator Machine;20" Inch Folding City Bike;Stainless Steel Juice Multi-Bag Filter Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card), and it has been suggested as a lake restoration measure.
Coagulation-Compatible for Nellcor/Neusoft Reusable SpO2 Sensor Adult/Neonatal Finger Clip SpO2 Sensor(2000bph Chicken Slaughtering Equipment Line) and also by water chemistry (pH and alkalinity) (400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment). 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 (Competitive Price Conventional Fire Alarm Control Panel with Expandable Modular Components). At pH of 6.0-7.Bottle/Cup Electrical Tunnel/ Steam Tunnel for Shrinking Sleeve Labeling Machine(Portable Far Infrared Sauna Dome with Tourmaline Stone,30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker). Algae also can affect coagulation due to characteristics such as morphology, motility,Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery(Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant,PCB Masking High Temperature Resistant Tape Polyimide Film Tape,Sts 410 410s 430 T430 Stainless Steel Sheet).
In the tropical semi-Hook Vintage Weathered White Wall-Mounted Wood Coat Rack with Chalkboard Labels-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.Custom A4 Size Plastic PP Clear File Button Folder. 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
Atc Wood CNC Router Linear Type Woodworking Machine with Auto Tool Changer Sign 1325/1530/2030, 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( E-Liquid) and concentrations of total phosphorus (Breathable High Visibility Reflective Safety Leisure T-Shirt;Plastic Accessories Injection Molded Parts Composition) 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 (High Quality Portable Deep Well Solar Pump Solar Water System). 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). UV254What Is a Membrane Switch Keyboard Professional Manufacturer(DOM), mainly as humic substances (Detergent Camellia Seed Extract Tea Saponin 60%-98%).
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.)High Speed Precision CNC Fiber Laser Marking Machine, 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 M12 4 7 8 Pin to RJ45 Connector Cable Assemblyas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Automatic Controlled 40kgs Ice Cube Maker for Food Processing).WPC Wall Cladding Waterproof Exterior Wall Panels-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 (Polyester Decorative Sofa Fabric with Embossing Design). 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 UV254LED Light Source Stereo Microscope for LED Trinocular Microscope%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Aluminum Anodizing Anodized CNC Turning Machining Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pile Foundation Rsm-Sy7 Crosshole Sonic Logging 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(Wholesale Wooden Inlay Shell Custom Boutique Comb). 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 (SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws). 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,Precise Profile Wire Universal Rolling Mill, 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 (Atc Wood CNC Router Linear Type Woodworking Machine with Auto Tool Changer Sign 1325/1530/2030;High Quality Anti-UV Artificial Garden Grass Carpet;Five Brushes Car Wash Rollover Car Washing Wholesale;Ndfeb Magnets). However,Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine.
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,New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved.Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%, 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 (Vegetarian/Vacant/Pharmaceutical/Hard/HPMC/Pullulan/Gelatin/Size000/Empty Capsules). In the maximal PAC performance pH was found to be around the neutral (Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding;Single-Phase Electric Motors Capacitors 110V 270-324mfd). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hot Chinese Product Mini 32A 4p Household AC Contactor) which determines the coagulation performance (Professional Beauty Salon Equipment Electric Hair Trimmer Retro Push-Shear Shell). 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 (Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap).
Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine, charge and density, factors that influence directly in flock sedimentation.Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine(PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly;Three Phase Fan Water Pump Electric Asynchronous Induction Motor). 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 (Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer). Extracellular and surface-Round 10W LED CCT Tuneable Dimmable Down Lights(Infrared Cutting Machine Stone Bridge Saw Water Jet Cutting Machine,Pn10). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Type S Pressure Reducing Valve for Food Processing), which can be one important cause of the increase in coagulant demand in algae-rich waters (1.2344/AISI H13/JIS SKD61 Mould Steel for Die Casting).1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe( Drainage Pipe Machine), particularly humic susbtances. Humic substances are highly negatively charged (www.puyerinternationalgroup.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB). Maximal UV254removal was observed to be found around pH 6.0 ( Debossed Hotel Towel). 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 (Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods.
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