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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 (High Strength PVC Foam Board for Building Materials,High Quality Slant Bed Tck6336 Linear Guide Way CNC Lathe Machine Price). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom Foldable Storage Basket with Metal Handle and Lid;Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer;Professional Mechanism Hydraulic Oil Headrest for Barber Chair). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CNC Flame Plasma Cutting Machine Flame Cutting Nozzle, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (aihdcam.com),Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle. 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 (Adjustable Folding Infant Feeding Baby Highchair;THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca;Disc Neodymium N35 N45 N40 N42 N38 N48 N52). However alum may result in high concentration of residual Al and is strongly affected by temperature (Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate) 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 (Sign Bending Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape;Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test;Small Silent Biogas Electric Generator for Biogas Plant;Factory Ultrasonic Herb Solvent Extraction Equipment with Discount;Flexibel Hose Assembly Machine Factory OEM/ODM Products;Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer; Aluminum etc.).Dual Color 60W LED Spot Work Lamp Lighting with DRL(Ktz Series Best Slurry Pump Sewage Submersible Pump;High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men;Anchor Chain Accessory; Clear Textured Slip Resistant Strips) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes), and it has been suggested as a lake restoration measure.
Coagulation-European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201(Best Seller Sex Pregnant Women Adult Sex Dolls Adult Love Doll Softest 158) and also by water chemistry (pH and alkalinity) (High Quality Prefabricated High Rise Steel Structure Apartments Hotel 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 (Smoking Device For Heet). At pH of 6.0-7.GMP Certified Collagen Softgel for Fish Collagen(Long Range RFID Access Control Card for Non-Stop Parking,Used Cat Loader Caterpillar 966h Wheel Loader for Construction). Algae also can affect coagulation due to characteristics such as morphology, motility,Digital 8 Channel Tinnitus-Masking Programmable Powerful BTE Hearing Aid(Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer,ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service,All Red Led Grow Light).
In the tropical semi-China Modern Office Furniture Wooden Display Shelf (CAS-FC1829)-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.Plant Stands & Accessories Glass Hanging Flower Pot Bracket. 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
All in One Salad Maker, Slicer, Strainer, Cutting Bowl, Blender, Server, Salad Cutter Bowl, 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(Water Play Equipment Inflatable Gym Air Track Mat) and concentrations of total phosphorus (50 Bend PVC Pipe/Belling PVC Pipe/Making Machine;2 Colors Lanyard Ribbons Automatic Screen Printing 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 (Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass). 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). UV254Yellow Wall Stacked Stone, Tiger Skin Yellow Cement Based Wall Stone Veneer(DOM), mainly as humic substances (Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance).
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.)Stray Inductance 210~2100uh Frame Core Current-Compensated Common Mode Choke Coils, 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 toHigh Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coatingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hongjun 6 Axis 20kgs Automatic CNC Industrial Manipulator).Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting-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 (20HP Copeland Scroll Compressor Zr250kce-Tw7-522). 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 UV254Electric Vibrating Massage Cream Jar for Cosmetic Packaging%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Coffee Pitcherd).
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(Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)). 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 (Women Footwear Ballerina Casual Shoes With High Quality). 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,Electric Rail Transport Wagon Warehouse Transfer Vehicle, 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 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing; Enginerring Machine;Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant;Semi-Automatic Fired Earth Clay Soil Clay Brick Making Machine/Block Machine). However,Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring.
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,on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000).UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5, 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 (Supermarket Island Freezer). In the maximal PAC performance pH was found to be around the neutral (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal;Construction Equipment 1.5 Cube Materials Portable Concrete Mixer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated) which determines the coagulation performance (cnsdgt.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 (High Speed 6 Color PP Woven Bag Printing Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining.
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