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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 (Small Silent Biogas Electric Generator for Biogas Plant,China Manufacturer Grinding Tool Metal Grinding Plate and Circular Concrete Grinding Wheel). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Ultrasonic Herb Solvent Extraction Equipment with Discount;Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer; Aluminum etc.). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Ktz Series Best Slurry Pump Sewage Submersible Pump). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Elastic Nylon Breathable Arm Elbow Sleeve for Sports, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automatic Bagging and Weighting Machine Packing Filling Machine),Ladies Fashion PU Leather Mini Backpack for Girles. 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 (High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men; Clear Textured Slip Resistant Strips;Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes). However alum may result in high concentration of residual Al and is strongly affected by temperature (Best Seller Sex Pregnant Women Adult Sex Dolls Adult Love Doll Softest 158) 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 (Flexible Circuit Boards). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building;Long Range RFID Access Control Card for Non-Stop Parking;Used Cat Loader Caterpillar 966h Wheel Loader for Construction;Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer;Fireproof Aluminum Foil Tape or Fsk Tape with Strong Adhesive;ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service;Stainless Steel Galvanized Perforated Metal Sheets).Factory Price Diesel Water Pump for Mine Dewatering(Best Factory Price Metallic Honor Medal with Neck Ribbon;Water Play Equipment Inflatable Gym Air Track Mat;Pop Card Design;50 Bend PVC Pipe/Belling PVC Pipe/Making Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards), and it has been suggested as a lake restoration measure.
Coagulation-Most Popular Android Satellite Receiver Android DVB S2 Cccam(Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder) and also by water chemistry (pH and alkalinity) (Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass). 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 (Percision Stainless Steel 316/304 Metal Stamping Suppot Strip). At pH of 6.0-7.3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist(Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance,Hot High Quality Self Service Car Wash Equipment). Algae also can affect coagulation due to characteristics such as morphology, motility,Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13(Pedstal Electric Stand Fan 5 Speed Control Air Cooler,Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube,Organic Fertilizer Packing Machine).
In the tropical semi-Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine-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.High Density Wood Grain Fiber Cement Board. 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
Waterproof Spunbonded Flame Retardant Fabric for Function Textile, 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(Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao) and concentrations of total phosphorus (20HP Copeland Scroll Compressor Zr250kce-Tw7-522;Wz30-25 Backhoe Wheel Loader with Ce Approval) 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 (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)). 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). UV254The Factory Sells Low Price and High Quality Desulfurizer Powder(DOM), mainly as humic substances (Women Footwear Ballerina Casual Shoes With High Quality).
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.)Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle, 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 to Enginerring Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cnc Lathe Turning).Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser-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 (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal). 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 UV254Factory Customized Marathon Athletics Football Awards Medallion Metal Medal%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Construction Equipment 1.5 Cube Materials Portable Concrete Mixer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Blow Mould For Ip Ducts For Car Air Conditionerd).
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(High Speed 6 Color PP Woven Bag Printing Machine). 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 (Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors). 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,Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies, 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 (Disposable TPE Gloves;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top;1.2V 3600mAh 4/3A size rechargeable NiMH Battery;Standard Sizes Aluminium Galvanized Mild Steel U Channel). However,Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors.
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,Ce Approved Cheap Medical Disposable Electrical Infusion Pump.1000kg/Day Ice Making Machines Custom Ice Cube Machine, 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 (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS). In the maximal PAC performance pH was found to be around the neutral (High Energy Ejector Venturi Gas Scrubber System;Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising) which determines the coagulation performance (Stainless Steel 316 Explosion Proof Air Electric Control Solenoid Valve). 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 (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field.
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