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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 (3.0mm Standard FC Fiber Optic Connectors for Data Processing Networks,China High Quality Synchronous Belt Pulley). As a result, several chemical methods have been applied to control P internal loading worldwide ( Porcelain &Enamal Plate Bowl and Cup;Copper Antique Beverage Party Tub Ice Bucket Wine Cooler;Hydraulic Small Boat Marine Deck Crane for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Food Processing Industry Fruit Vegetable Drying Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Modern Style Prefabricated Steel Structure Poultry House, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Led Ring Light),Made in China Colored Heat Resist Strength Silicone Rubber O-Rings for Excavator. 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 (Printing Paper Coated Art Paper C2s/C1s Gloss/Matt Art Printing Paper;Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall;Hot New PC Polarized Sunglasses Manufacturers Direct). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Precision Durable Aluminum Cutting Saw Blade) 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 (www.billowtimewatch.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Blocking-Concealed Passport Holder RFID Wallet with Neck Strap;2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment;6 Panel Embroidered Fashion Fitted Cap Custom;Harem Sweat Sport Casual Women Pants for Jogger;Aaaaa-Rydmet Cemented Tungsten Carbide Bur Blanks-Bsa;Stupid Cow Indoor Coin Operated Arcade Video Vending Simulator Shooting Game Machine;Wholesale Price Brass Female Press Fitting with Tee Union).TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use(Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip;Poultry Farm Equipment Feeding System Made in China;www.alitruck.com;Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer), and it has been suggested as a lake restoration measure.
Coagulation-CNC Flame Plasma Cutting Machine Flame Cutting Nozzle(High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat) and also by water chemistry (pH and alkalinity) (Delight 15W Sensor+Night Sensor Solar Garden Lamp). 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 (Disposable Face Shield). At pH of 6.0-7.Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle(Vertical Gas Boiler for Water Heating in Biogas Plant,Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Dual Color 60W LED Spot Work Lamp Lighting with DRL(Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line,Ozone Generator Water Treatment Mineral Water Filter System,Top Sales High Quality 10A 12V 12V Solar Controller).
In the tropical semi-European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201-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.GMP Certified Collagen Softgel for Fish Collagen. 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
Digital 8 Channel Tinnitus-Masking Programmable Powerful BTE Hearing Aid, 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(Wall Mounted Air Purifier Ozone Generator for Home/Office) and concentrations of total phosphorus (High Speed Lead Edge Printing Slotting Machine;Agricultural Water Pump 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 (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll). 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). UV254China Modern Office Furniture Wooden Display Shelf (CAS-FC1829)(DOM), mainly as humic substances (P6.25 Interactive Dance Floor LED Display Screen).
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.)Plant Stands & Accessories Glass Hanging Flower Pot Bracket, 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 toW11H-20X2500 3 rolls Automatic plate industrial bending rolling machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.xzbl.com).All in One Salad Maker, Slicer, Strainer, Cutting Bowl, Blender, Server, Salad Cutter Bowl-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 (Modern Leisure Chair for Europe). 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 UV254Yellow Wall Stacked Stone, Tiger Skin Yellow Cement Based Wall Stone Veneer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Single Pole Female Lamp with Rotating Chimney Lamp Floor Lamp with Touch Dimmer Switchd).
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(Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa). 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 (New Baking Tool Creative Customized Silicone Toast Cake Mold). 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,Stray Inductance 210~2100uh Frame Core Current-Compensated Common Mode Choke Coils, 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 ( AC4900ca;Carbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washers;Waterproof Antislip PVC S Mat PVC Z Mat for Bath Swimming Pool Factory Price;Rav4 Key Case). However,Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting.
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,Electric Vibrating Massage Cream Jar for Cosmetic Packaging.Electric Rail Transport Wagon Warehouse Transfer Vehicle, 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 (Steel Drilling Water Well Filter / Bridge Slot Screen Pipe). In the maximal PAC performance pH was found to be around the neutral (Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars;C-Type 2 Piece Tin Can Making Punch Press Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer) which determines the coagulation performance (Thread Drill Bit Set). 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 (Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Js500 Twin-Shaft Concrete Mixer for Block Machine.
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