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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 (ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service,Factory Direct Sales Tungsten Carbide Alloy Circular Saw Blade Wood Cutter Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Galvanized Perforated Metal Sheets;Best Factory Price Metallic Honor Medal with Neck Ribbon;Water Play Equipment Inflatable Gym Air Track Mat). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (50 Bend PVC Pipe/Belling PVC Pipe/Making Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Synthetic Fiber Filter Rolls Filter Media for Air Conditioning, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ductile Iron Galvanized 8′′ Elbow 90 Degree with FM/UL Listed),1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine. 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 (Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards;Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder;Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass). However alum may result in high concentration of residual Al and is strongly affected by temperature (Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance) 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 (Foundation Makeup Brush). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot High Quality Self Service Car Wash Equipment;Pedstal Electric Stand Fan 5 Speed Control Air Cooler;Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube;High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating;A4 Button Envelope File Suppliers/Manufacturers for Sale;Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H);Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao).THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca(20HP Copeland Scroll Compressor Zr250kce-Tw7-522;Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop;Mixed Fruit Box;Professional Industrial Cr-V Combination Plier for Cutting) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)), and it has been suggested as a lake restoration measure.
Coagulation-China Manufacturers Round Welded Stainless Seamless Steel Pipes 316(Women Footwear Ballerina Casual Shoes With High Quality) and also by water chemistry (pH and alkalinity) (250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps). 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 (Hospital Medical Emergency Trolley Hot for Sale). At pH of 6.0-7.Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price(3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable,Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing). Algae also can affect coagulation due to characteristics such as morphology, motility,Foshan Manufacturer Bathroom Glass Sliding Door Roller( Enginerring Machine,Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant,Precision Metal Stamping Die).
In the tropical semi-4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening)-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.Industrial RO Water Purification-1500gpd with Black Cabinet (0.25T/H). 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
Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller, 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(Construction Equipment 1.5 Cube Materials Portable Concrete Mixer) and concentrations of total phosphorus (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;Ss400 Tube) 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 (600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag). 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). UV254Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition(DOM), mainly as humic substances (1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable).
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.)Manufactured Goods PPGI Coil Corrugated Steel Sheet, 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 to12V 1A Constant Voltage LED Power Supply with Ce FCC RoHSas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Style Imported Medical Aesthetic Shr IPL Hair Removal Machine).Organic Fertilizer Production Line for Manure Treatment-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 (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). 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 UV254500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring 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 (Transtones Cut-to-Size Stone Slab Lighting Panel for Interior Decorsd).
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(Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry). 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 (RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats). 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,Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal, 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 (Ideabond Aluminum Composite Panel Brushed Series;Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation;China OEM Cast Iron Tractor Farm Clutch Pulley;15mpa Gate Valve). However,Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine.
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,Genuine 1m USB Date Charging Cable for iPhone.12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch, 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 (3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench). In the maximal PAC performance pH was found to be around the neutral (Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking Machine;Aluminum Recovery Fill Tank for C-4 84-96 Chevrolet Corvette). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2017new Custom Wooden Jewelry Packing Box of Ring/Necklace/Pendant/Earring Storage Box) which determines the coagulation performance (Solar Powered Outdoor Light). 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 (WPC Wall Cladding Waterproof Exterior Wall Panels).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands.
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