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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 (China Wholesale Hydraulic Industrial Winch for Mining Well,Christmas Decorative Xmas String Fairy Curtain Strip Garlands Party Lights). As a result, several chemical methods have been applied to control P internal loading worldwide (LPG Gasification Pressure Regulating Skid in Mobile Station Building;3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler;Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fashionable New Products Twin Screw Extruder for Pet Recycling). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Smooth Surface Black HDPE Sheets for Wastewater Treatment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Monopolar Cautery Pencil),Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel. 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 (5/8 Inch Stainless Steel Banding in Plastic Tote;Electric Rail Transport Wagon Warehouse Transfer Vehicle;Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating 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 (8.2mhz Easink Tag Safety). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Low MOQ Perfect Binding Soft Cover Book Printing High Quality;24V/48V 40A/80A MPPT Solar Charge Controller for Solar Power System;Aluminum Oxide Abrasive Products 5 6 Stone Metal Disc Grinding Wheel;Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21);Health Raw Material Creatine Pyruvate CAS No.: 55965-97-4 with High Quality;Amino Acid Magnesium Chelate for Organic Fertilizer;Nc Hydraulic Bending Tube Metal Pipe Bending Processing).High Precision Injection Molding Plastic Parts in China (STK-PL-1055)(Best Quality Plastic Wall Plug Expansion Anchor;700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346);12 Inch Cast Iron Centrifugal Pump;Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Outdoor Waterproof IP68 LED Structure 3D Arch Street Christmas Decoration Ball Motif Lights), and it has been suggested as a lake restoration measure.
Coagulation-Fan Cooling Oval Design Commercial Cake Display Showcase Fridge(Home Used Portable Fencing Aluminium Swimming Pool Safety Fence) and also by water chemistry (pH and alkalinity) (40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine). 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 (F40129 Hot Selling Aftermarket Alloy Wheels Rims). At pH of 6.0-7.Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable(2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC),Promotion LCM Custom LCD Display Stn FSTN Cog LCD Positive Graphic LCD Display Module for). Algae also can affect coagulation due to characteristics such as morphology, motility,CNC Machine Linear Guide Accordion Bellows Cover(94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent,Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump,Various Shapes and Colors Available Polyester Fiber Screen).
In the tropical semi-White/Gray Colors U-PVC Water Supply Pipe for Plumbing System-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.Microfiber Towel Quick Dry Towel Set for Beach, Travel, Swim, Pool, Camping, Outdoors and Sports. 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
Seamless Steel Rolled Ring, Forged Steel Rings for Large Diameter, Manufacturer of Slewing Ring, 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(22mm 2no2nc Metal on off Start Button Power Push Button Switch) and concentrations of total phosphorus (Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India;Mini Essential Oil Glass Bottle) 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 (Solid Carbide Hinge Boring Bits Wood Router Bits). 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). UV254Inconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipe(DOM), mainly as humic substances ( Wall Rack).
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.)Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic, 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 toLED Light Source Stereo Microscope for LED Trinocular Microscopeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot Promoting Food Additives Anhydrous Calcium Acetate).Customized Disposable BBQ Bamboo Round Stick and Skewers.-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 (Mini Horizontal Axis 100W Wind Generator Turbine). 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 UV254Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Environmentally Friendly EPE Foam Plank Extrusion Machine for DIY Toysd).
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(Scafold Replacer High Efficiency Spider Lift Articulating Boom). 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 ( Steel Pipe). 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,Sesame Almond Cashew Nut Peanut Butter Making Processing Machine, 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 (High Speed Double Jersey Computerized Transfer Rib Circular Knitting Machine 2/3 Ways Djjtr; Custom Fire Burner Rings;High Reputation Manufacturing Plant Precast Concrete Steel Pole Mold Sale;Unbreakable Ozone Generator for Desiccant Chemical Storage Room Disinfecting). However,Big Engine, Large Output Forestry Application Biomass Wood Chipper.
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,LED Lighted Mirror with Bluetooth Functions.Br42 Red Color Mushroom Head Push Button Switches, 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 (New Design Neoprene Beer Can Cooler). In the maximal PAC performance pH was found to be around the neutral (Cheap Price Woodfree Offset Writing Printing Paper;High Quality XCMG Truck Mounted Crane Sq3.2sk1q/K2q in The Philippines). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack) which determines the coagulation performance (Cnc Precision Machining). 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 (Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66).
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