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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 (Customizable High Quality Q38 Series of Catenary Shot Blasting Machine,LED Moving Head Spot 30W Gobo Spot DJ Disco Light). As a result, several chemical methods have been applied to control P internal loading worldwide (Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder;PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector; Fabric). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3m 467MP Strong Adhesive Double Sided Transfer Tape). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,IPS No. 6 Dtp Automatic Smart Wrist Watch 2019, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (12038 Brushless DC Cooling Fan Industrial Equipment DC Ventilation Fan),S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer. 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 (Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader;Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor;Biodegradable Resealable Plastic Food Packaging with Zipper). However alum may result in high concentration of residual Al and is strongly affected by temperature (Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration) 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 (e scooter). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt;Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory;Professional Neck Jacquard Woven Lanyard Strap;Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck;Degergent Grade Cmc Powder; Pullover Fleece Tie Dye Hoody;Customized Machine Dustproof Bellow Cover for The CNC Guide).Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer(Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve;Stainless Steel for Indoor Wall Construction Materials;Wholesale Custom Printing BOPP Packing Adhesive Packaging Tape;Photo Album Self Adhesive PVC Foam Sheets for Inner Pages) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037), and it has been suggested as a lake restoration measure.
Coagulation-Custom Outdoor Event Pop up Canopy Easy up Advertising Tent(Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine) and also by water chemistry (pH and alkalinity) (Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook). 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 (Heavy Duty Sliding Door Roller). At pH of 6.0-7.Customized Various Aluminum Hardware Fastening/Real Accessories(Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal,Gear Box Forged Steel Bw Ends Full Welded Ball Valve). Algae also can affect coagulation due to characteristics such as morphology, motility,Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil(Organic Waste Gas Treatment Device Gas Disposal on Hot Sale,Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room,100% Polyester Fabric Roll).
In the tropical semi-High Quality Humidity Control Chamber Artificial Climate Chamber-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.CNC Precison Red Painting Titanium Alloy Machinery Parts. 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
I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds, 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(Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label) and concentrations of total phosphorus (Complete Wood Pellet Line Sawdust/Straw/Biomass Pellet Plant;Quad Seal Snack Packaging 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 (Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s). 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). UV254New Design Contact Infrared Baby Ear Thermometer Jl0158(DOM), mainly as humic substances (Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw).
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.)Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag, 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 toCheap Price Creative Style Design of Men′s Leather Slippersas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hollywood Makeup Mirror).OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector-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 (Bathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drain). 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 UV254Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rainbow Rafting Fiberglass Aqua Water Park Slide). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Noodles Instantd).
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(Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)). 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 (LED Lighted Mirror with Bluetooth Functions). 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,Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM, 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 (Plastic Fork Mould for Cake Disposable Tableware Injection Molding;Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6;Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment;Soda Ash Light). However,Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects.
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,Permanent Magnetic Grid for Europe Market.New Fitness Commercial Exercise Spinning Bike, 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 (HR/CR/GI High Frequency Longitudinal Seam Tube Mill). In the maximal PAC performance pH was found to be around the neutral (Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4);Small Scaled Laboratory Pharmaceutical Dry Mixing Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Outdoor High Pressure Isolating Vacuum Load Switch) which determines the coagulation performance (Steel H Beam Structure Workshop (Q345B/Q235B)). 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 (Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale).
Ce Approved Disposable Paper Mask, 2 Ply Beauty Face Mask, charge and density, factors that influence directly in flock sedimentation.Vertical Gas Boiler for Water Heating in Biogas Plant(Full Car Key for Chrysler 5+1 Button Remote Control;Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt). Extracellular and surface-CO2 Laser Engraving Cutting Machine for Acrylic(www.asiamzsteel.com,High Quality Korea Standard Door Core Material LVL). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Hight Quality Air Filter C1250 for Mann and Atlas Air Compress), which can be one important cause of the increase in coagulant demand in algae-rich waters (Cut and Impact Resistant Hand Protection Glove).Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts(Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System), particularly humic susbtances. Humic substances are highly negatively charged (Ball Valve Dn50), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Self-Adhesive Non-Slip Sticky White Felt for Easy Painter). Maximal UV254removal was observed to be found around pH 6.0 ( Round Jaws Lock Wrench Wr Type). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Double Screws Textured Soy Protein Artificial Meat Tvp Tsp Extruder).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A).
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