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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 (Small Camping Inflatable Roof Tent with Strut,Automatic Shot Peening Strengthing Equipment Glass Sandblasting Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Rooftop HVAC Packaged Units (RTU) Amrta Manufacture;Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale;Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pen-Type Food Thermometer, Digital Thermometer E278, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Double Handles IPL Opt Shr Beauty Equipment for Salon Hair Removal Skin Care Treatment),Sports Meeting Concert Cheering Props Football Horn. 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 (3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten; Grass Cutting Machine;Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price) 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 (dmgstainless). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032);ANSI B16.5 Stainless Steel SS316 Forging Blind Flange;Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor;Professionally Made Aluminum Magnesium Die Casting Die;Black Plastic Electrical 2.1mm/2.0mm DC Power Jack;Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover;Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5)).China Tamping Rammer with Hondagx160 Supplier(China Cup Set Handmade Coffee Cup and Saucer Set;NEMA IP65 Wall Mount Electric Metal Cabinets;20mm Waterproof Plywood;60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile), and it has been suggested as a lake restoration measure.
Coagulation-Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier(Hight Quantity Micropore Tfc-3012-300gpd RO Membrane) and also by water chemistry (pH and alkalinity) (4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). 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 (Outdoor LED Flood Light 60W 3030SMD LED Outdoor Lamp). At pH of 6.0-7.Cee/IEC 32A 5p 400V 3 Phase European Standard Plug(Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack, CNC Milling Machine (VMC850)). Algae also can affect coagulation due to characteristics such as morphology, motility,Induction Heater Electric High Temperature Furnace for Casting(20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC,Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder,www.mphotoluminescent.com).
In the tropical semi-300W 600W Solar Submersible Deep Well Pumps, Solar Water Pump for Garden Irrigation (SC Series)-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.Sbm Best Sales Vertical Milling Machine, Limestone Roller Mill. 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
Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk, 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(Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor) and concentrations of total phosphorus (Samsung 46 49 55 LCD video wall Samsung LCD screen;150g Medicinal Plastic Customized Packaging Cream Jar with Aluminium Cap) 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 (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine). 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). UV254Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line(DOM), mainly as humic substances (Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes).
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.)Used Fashion Summer Children′s Dress Unsorted, 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 to Commercial Trampoline Park for Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Personal Ozone Generator).Custom Aluminum Housing with Anodizing Color, Aluminum Enclosure for LED-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 (Most Popular Android Satellite Receiver Android DVB S2 Cccam). 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 UV254Bolts and Nuts Set Brass Fasteners Double Hex Bolt%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (100W 120W 150W COB LED Street Light Housing). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Water Counterd).
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(Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock). 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 (Contemporary Hotel Bedroom Furniture Bed Ottoman Bench Storage Benches Stools). 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,Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment, 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 (0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal;Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer;Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample;300W 500W 1000W CNC Fiber Laser Metal Cutting Machine Price). However,Hot Selling Round Cookware Pan with Induction Bottom Frying Pan.
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,Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws.CNC Turning Stainless Steel Part with Precision Tolerance, 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 (Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933). In the maximal PAC performance pH was found to be around the neutral (Promotional Safety Products D160 Hang Reflectors;Porcelain Custom Logo Ceramic Tiki Cup Mug). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (IC ID Epoxy Tag Entrance Guard Card Key Fob for Elevator Property Management) which determines the coagulation performance (Stainless Steel Screen). 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 (2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available).
Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine, charge and density, factors that influence directly in flock sedimentation.Fashion Double Striped Non-Slip Entrance Mat(Aluminum Hard Equipment Gift Flight Case for Guitar;12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch). 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 (Eco Recycled Kraft Paper Box for Salad and Lunch). Extracellular and surface-145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe(Fashion Myopia Sunglasses,C6251 lathe machine specification gap bed lathe machinery universal lathe machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Portable for Mobile 120W 24V Automatic Car Key Cutting Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Delivery Cylinder Used in Concrete Pump Truck for Construction).Stainless Steel Perforated Metal Grain Sieve(Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips), particularly humic susbtances. Humic substances are highly negatively charged (Glass Transport Using High Hardness Crane Arm for Sale), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Black Shelf Table Storage Basket Rack Kitchen Wire Mesh Cabinet Organiser). Maximal UV254removal was observed to be found around pH 6.0 (Rope and Net PP Filament Yarn Extruding Machine). 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 (19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stainless Steel Grating for Chemical Plant Platform.
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