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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 (Expert Supplier Of Stainless Steel Electric Cooking Pot,shoulder pack Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (Training Mat Floor/Inflatable Gymnastic Mat/Jumping Mat for Kids;Popular Environmental Plastic Vinyl Spc Floor Tile;Eastcooler 10X2.5 Water Filter Granular Active Carbon Filter Cartridge). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (18650 Cylinder Cell Case with Anti-Explosive Cap and Insulation O-Ring). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (A6 Kraft Notebook),Kw-700 Industrial Commerical Driving Type Floor Scrubber Price. 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 (Factory Price Chenille Sunscreen Sheer Fancy Curtain;Manufacture Leather Strap Japan Movt Stainless Steel Back Watch (cm19092);dual Row 15pin D-SUB Mechined PCB Mounting Power Connector). However alum may result in high concentration of residual Al and is strongly affected by temperature (Industrial Unit Cooler / Evaporative Air Cooler / Evaporator) 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 (Household Activated Carbon Water Filter Cartridge Home Used in Water Treatment). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008);Factory Supply Cheap Custom Bleached White Cotton Gloves;Hot Selling 2019 510 Thread 350mAh Vertex Battery;China Touch Screen for iPhone 6s LCD Touch Screen Digitizer;Jqhsp50*12 Air Winch with Automatical Spooling;Srz Industrial Radiator;130kg/M3 Plastic PVC Core Foam for FRP Vacuum Infusion).Ribbed Colorful Wall Plug Anchor with Screw( Metal Duct Machine;Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag;Custom Shaped Books;Tungsten Carbide Milling Insert for Book Binding) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PC Black Plastic Material Polycarbonate PC Granules Resin), and it has been suggested as a lake restoration measure.
Coagulation-Plastic Fork Mould for Cake Disposable Tableware Injection Molding(3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration) and also by water chemistry (pH and alkalinity) (3m 1500 Electrical Pipe Wrap Tape Vinyl PVC Coated Wire Insulation Tape). 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 (Tea Pot And Kettle Set). At pH of 6.0-7.28dBi 1575.42MHz BNC Connector Active GPS Antenna(11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte),Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet). Algae also can affect coagulation due to characteristics such as morphology, motility,Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush(Plastic Valve with The Membrane Heat Welding Machine,Front Lifting Used Tipper Second Hand Dumper Volvo Dump Truck Original From Sweden,Double Colors Flocculent 60mm Rubber Balls).
In the tropical semi-Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm-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.China Manufacture 2mm3mm5mm Thickness Round Wall Mirror for Sale. 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
240L German High Capacity Shopping Trolley with Baby Seat, 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(Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption) and concentrations of total phosphorus (High Quality Double Link Ra DVI D 24+1 Pin Connector;CO2 Laser Marking Machine for Plastic Tag Label Printing) 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 (Best Quality Hydroponic Film Greenhouse Steel Structure Construction). 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). UV254Disc Neodymium N35 N45 N40 N42 N38 N48 N52, Wholesale Magnet, Magnets in Ningbo(DOM), mainly as humic substances (Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure).
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.)Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle, 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 toForged Custom Exterior French Door Wrought Iron Double Entry Doorsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Auto Spare Parts).40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale-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 ( 4 Butanediol Bdo CAS 110-63-4 with Lowest Price). 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 UV25420FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Marine Studless Link Anchor Chain for Sales). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (skrscale.comd).
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(15t/H Hot Selling Professional Factory Price Palm Nut Crusher Machine with Ce). 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 (Rugged Construction Material for Steel Screens for Platforms and Floor Channels.). 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,Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty, 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 (Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB;Difference Between PPGI and PPGL of Price and Type; Dumper Truck;Decorative Wood Furniture Sticker PVC Wallpaper Self Adhesive Vinyl Removable Waterproof Wall Paper). However,Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074).
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,J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter.Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown, 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 ( ISO9001). In the maximal PAC performance pH was found to be around the neutral (Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence;Shenzhen Manufactory Specilized in LED Light Manufacturing Line Setup). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Floating Oil Seal 150-27-00020 Excavator Parts) which determines the coagulation performance (Customized Supplier High Quality Steel CNC Machining Lathe Turning Fastener). 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 (High Speed LDPE Polyethylene Plastic Film Extrusion Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect.
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