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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 (Swivel Hook Auto Engine Valve Spring Motor Spring,Black Throw Blanket). As a result, several chemical methods have been applied to control P internal loading worldwide ( Security Protected Razor Barbed Wire/Blade Barbed Wire;Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles;Galvanized Pullet Chicken Cage Baby Chicken Cages). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Portable for Mobile 120W 24V Automatic Car Key Cutting Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Custom Size Digital Printed Polyester USA National Flag),Fashionable New Products Twin Screw Extruder for Pet Recycling. 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 (CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories;Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment;Sheet Metal Stamping Galvanized Steel Panel and Frame). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine) 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 (Vinly Floor With Wood). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (IP65 8W Outdoor Integrated LED Street Light Solar Lamps;CNC Turning Stainless Steel Part with Precision Tolerance;Stainless Steel Rectangular Pipes for Balcony Guardrail;Modified Shipping Container House for New Zealand;Artifical Plant;Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven;THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC).V4 Type Sintered Porous Filter with Female Thread(Socket Type 2 32A 22kw EV Charging Point EV Charger for Electric Vehicle Charging;Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door;3m Reflective Sticker;2019 New Crop Blanched Peanut Kernels (long shape) From China) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Absorbent PP Mat Hardwearing Doormat with Round Shape), and it has been suggested as a lake restoration measure.
Coagulation-Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine(China Wholesale Hydraulic Industrial Winch for Mining Well) and also by water chemistry (pH and alkalinity) (LPG Gasification Pressure Regulating Skid in Mobile Station Building). 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 (Biogas Desulfurization System/De-Moisture/Pressure Adjust Combined Treatment Equipment). At pH of 6.0-7.Steel Drilling Water Well Filter / Bridge Slot Screen Pipe(3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler,Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling). Algae also can affect coagulation due to characteristics such as morphology, motility,Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System(Fashionable New Products Twin Screw Extruder for Pet Recycling,5/8 Inch Stainless Steel Banding in Plastic Tote,m.bmspd.com).
In the tropical semi-Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer-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.Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange. 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
Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set, 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(Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine) and concentrations of total phosphorus (Low MOQ Perfect Binding Soft Cover Book Printing High Quality;Bamboo Bathroom Vanity Cabinets) 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 (Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21)). 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). UV254Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel(DOM), mainly as humic substances (Amino Acid Magnesium Chelate for Organic Fertilizer).
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.)2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger, 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 toNaixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5 Axis Cnc Machining Services).SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66-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 (40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine). 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 UV254Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stainless Steel Hex Socket Cup Head Bolt Machine Screw M1.6-M20d).
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(94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent). 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 (Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump). 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,7.5HP Centrifugal Circulation Swimming Pool Water Pump, 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 (22mm 2no2nc Metal on off Start Button Power Push Button Switch;Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India;Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale;Chain Link Fence Zinc Coating). However,for Bahrain Market Hot Cafe Vending Machine F303V.
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,Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion.5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD, 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 (Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer). In the maximal PAC performance pH was found to be around the neutral (Solid Carbide Hinge Boring Bits Wood Router Bits; Wall Rack). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Gelatin Empty Gelatin Printed Empty Gel Caps Size 2) which determines the coagulation performance (m.swinysteel.com). 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 (Bodybuilding Supplements Polypeptide Hormones Injectable Peptides Ipamorelin CAS: 170851-70-4).
3 Way Manual Staple Gun with Staples for Hand Tools, charge and density, factors that influence directly in flock sedimentation.Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor(Fashion Jewelry Stainless Steel Rose Gold Gemstone CZ Ring SSR1948;LED Light Source Stereo Microscope for LED Trinocular Microscope). 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 ( Aluminum Enclosure for LED). Extracellular and surface-High Quality HVAC Exhaust or Supply Plastic Air Valve(Ce Certificate Plywood Veneer Lathe Manufacture,Luau Pinhole Glasses Promotional Sunglasses Yiwu Market (B3030)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Mini Horizontal Axis 100W Wind Generator Turbine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%).Programmable Ozone Aging Test Equipment for Rubber Cable Resistance(34mm 7 Grade Atlas Copco Marble Gauge Rock Drill Parts Tapered Button Bit), particularly humic susbtances. Humic substances are highly negatively charged (high quality TPU material for garments), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Scafold Replacer High Efficiency Spider Lift Articulating Boom). Maximal UV254removal was observed to be found around pH 6.0 ( Steel Pipe). 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 (Mild Price A36 1.0425 ASTM A214 Seamless Carbon Steel Tube).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Manganese Mn13cr2 Mn18cr2 Jaw Plate Crusher Parts.
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