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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 (Air-Cooled Refrigeration Condenser Dual Flow Unit Cooler Air-Cooled Condensing Unit,Wg9000360152/3 Foot Brake Valve for HOWO Steyr Truck). As a result, several chemical methods have been applied to control P internal loading worldwide (14 X 14 Mesh Window Screen Aluminum Alloy Wire Netting;Food Safety Testing Equipment for Heavy Metal in Food Analysis;Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (factory outlet excellent herbicide DIURON 80% WDG on sale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom High Quality Winter Newsboy Beret IVY Cap for Men, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (etc.),VOD 1550nm Direct Modulated Optical Transmitter RF Input Local Program. 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 (Large Outdoor Water Park Slide/Water Turntable Amusement Equipment;Pond Electric Copper Wire Clean Water Pump with European Plug;Customized Disposable BBQ Bamboo Round Stick and Skewers.). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel) 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 (Ce Approved Farm Equipment 22HP ATV Flail Mower for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment;Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line;CNC Fiber Laser Marking/Engraving Engraver for Metal and Nonmetal;18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill;18 Gauge Black Wire;High Drying Efficiency Wood Sawdust Dryer for Sale;Exported Screw Eye Ground Anchor for Electric Fence Using).High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat(Contemporary Outdoor Garden Furniture Rattan Wicker Leisure Balcony Sets with Round Bed;Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb);Diy Solar Fountain Pump;Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ((1.5/2/2.5 /3/4/12 inch) Aluminium Hot Dipped Square Galvanized Pipe for Equipment Machine), and it has been suggested as a lake restoration measure.
Coagulation-XBD Series Single-Stage Single-Suction Fire-Fighting Pump(New Design Export Fiberglass Adult Water Bike for Sale) and also by water chemistry (pH and alkalinity) (Permanent Magnetic Grid for Europe Market). 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 (Landscape Light). At pH of 6.0-7.Hr-1800 PP Knitting Bag Sewing Machine, PP Woven Bag Making Machine(Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts,Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier). Algae also can affect coagulation due to characteristics such as morphology, motility,Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag(Uncoated Test Liner Fluting Medium Paper for Box Packaging,Carpet Grain UV Coating Eco-Friendly Fireproof Waterproof Spc Flooring1871,Hydraulic Cold Forming Tee Machine Suppliers for Sale).
In the tropical semi-Hot Sale 250ml Green Dorica Glass Olive Oil Bottle-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.Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine. 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
Kraft Paper Food Tray for Party, Camping, Carnival, BBQ, 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(Stainless Steel Male Female Screw Fasteners Connecting Book Screws) and concentrations of total phosphorus (Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191;Sliding Shelf Brackets) 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 (Fast Inflatable Air Bag Sofa Lounge Lazy Chair Bag Camping Bed Beach Hangout). 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 Speed Metal Pipe Automatic ERW Welded Pipe Machine(DOM), mainly as humic substances (Dr3008 Male&Female NPT Swivel Type Metal Brass Ferrule Valves).
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.)Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler, 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 toDisposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Ventas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aluminum Cup Washers).5ton 10m Competitive Price High Quality New Telescopic Forklift, Telehandler-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 (Fancy Personalized Charm Simple Crown Trendy 925 Sterling Silver White Gold Bracelet). 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 UV254Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (5X5m Aluminum High Peak Gazebo Pagoda Tent for Events). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Injection Moldd).
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(PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence). 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 (Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle). 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,Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware, 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 (Hot Selling Wireless Cell Phone Charger for Android Ios;Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring;Cheaper Polyester Cord Strap Factory Made in China;G Amino Acid). However,Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe.
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,Extra White Masterbatch 60% Anatase TiO2 for PE Films.Taiwan Swiss Type CNC Wheel Lathe Ck50L CNC Slant Bed Lathe Turning Lathe Machine, 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 (AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine). In the maximal PAC performance pH was found to be around the neutral (Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment;Special Flower Shaped Sterling Silver Cubic Zirconia Earring for Lady Wedding Gift). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling) which determines the coagulation performance (herb jar). 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 (Good Price and High Quality Crawler Crane Excavator Bearing).
HVAC Duct Making Machine, Metal Duct Machine, Auto Duct Line 3 for Sale, charge and density, factors that influence directly in flock sedimentation.Bodybuilding Supplements Polypeptide Hormones Injectable Peptides Ipamorelin CAS: 170851-70-4(Three Layers ABC Co-Extrusion PP Film Blowing Machine;Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass). 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 (Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm). Extracellular and surface-Fast Speed Packing Machine Small Candy Packaging Machinery Price(Die-Cast Aluminum High Power Flood Light LED 50 Watt,Kaishan YT23D Forging Air Leg Support Rock Drill Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Polished Solid Egypt Sunny Beige Marble Columns), which can be one important cause of the increase in coagulant demand in algae-rich waters (Multi-Functional Universal Mount LED Brake/Turn/Tail Lights).Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong(Natural Color of 100% 7A Malaysian Human Hair), particularly humic susbtances. Humic substances are highly negatively charged (Full Pu Type Running Track), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (49 Electric/Electrical Synchronous AC Gear Motor for Stage Light/Oven). Maximal UV254removal was observed to be found around pH 6.0 (New Design Brass IP68 LED Underwater Fountain Light). 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 (Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Flexible DC12V/24V SMD 2835 Blue Christmas Light LED Strip.
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