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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 (Yuanchen Nonwoven Needle Punched PPS Filter Felt,Low Price 220V 2W Series Electric Solenoid Water Valve). As a result, several chemical methods have been applied to control P internal loading worldwide (Waterproof Spunbonded Flame Retardant Fabric for Function Textile;Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000;Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Metal Computer Desk),Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer. 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 (10kw 20kw 30kw 50kw Small Gas Generator for Home Use;Fastener Screw /Self Tapping Screw / Machine Screw;Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper). However alum may result in high concentration of residual Al and is strongly affected by temperature (Plastic Cable Electric Plug Making Machines Supplier) 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 (Display Bulk Wicker Baskets). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel;Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner;Multifunction Massage Rainfall Shower Column with Five Functions;Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings;Whole House Lbo-B60 2p 375V Lightning Arrester Surge Protector;20PCS Porcelain Dinnerware with Popular New Design;Electric Control Polystyrene Cuttrt EPS Block Cutting Machine).Custom Outdoor Event Pop up Canopy Easy up Advertising Tent(Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516);DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling;Pallet Truck Lift;Spectrum Analyzer for Ferrous and Non-Ferrous Metals) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Dust Proof Window Screen Mesh Aluminum Wire Mesh), and it has been suggested as a lake restoration measure.
Coagulation-Customized Various Aluminum Hardware Fastening/Real Accessories(Car Air Compressor Tire Inflator Pressure Gauge) and also by water chemistry (pH and alkalinity) (70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204). 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 (Acetic Acid Food Grade). At pH of 6.0-7.Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil(Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent,High Precision 3D Printer Kit). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Humidity Control Chamber Artificial Climate Chamber( Limestone Roller Mill,High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine,Prepaint / Aluminum Coil).
In the tropical semi-CNC Precison Red Painting Titanium Alloy Machinery Parts-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.I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds. 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
New Design Contact Infrared Baby Ear Thermometer Jl0158, 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(Custom Engraved 2D Metal Volleyball Medals) and concentrations of total phosphorus (Ride on Concrete Power Trowel Machine with Suitable Seat;Automatic Plate Rolling Machine) 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 (Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom). 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). UV254Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag(DOM), mainly as humic substances (10.5 Inch Silicone Straws and Stainless Steel Straws).
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.)OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector, 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 toIndurstry Building Safety Boots with Steel Toe Cap and Midsole (SN1629)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High-Purity Calcined Alumina Balls for Catalyst Bed).Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine-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 (High Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray). 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 UV254Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Erw Steel Pipe Milld).
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(13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture). 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 (Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007). 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,Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects, 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 (Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels;P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;Galvanized Steel Air Pipe Ventilation Duct Tube;110/220/24V Air Conditioning Digital Temperature and Humidity Controller). However,Permanent Magnetic Grid for Europe Market.
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,New Fitness Commercial Exercise Spinning Bike.Ce Approved Disposable Paper Mask, 2 Ply Beauty Face Mask, 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 (CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine;Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases) which determines the coagulation performance (China Avilable instruments for school: skeleton model). 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 (Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.304 316 1.4301 1.4404 Stainless Steel Angle with Sharp Edge.
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