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 (Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon,High Frequency 4000rpm Engineering Machinery Electric Concrete Vibrator). As a result, several chemical methods have been applied to control P internal loading worldwide (for Bahrain Market Hot Cafe Vending Machine F303V;China Supplier PPGI Coils for Construction Materials;HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Accurate LCD Digital Medical Flexible Oral Thermometer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Custom T Shirt Maker),Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal. 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 (Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV;Panasonic Ai Spare Parts X004075 with Large Stock;Ceramic Components Applied in Machinery Industry). However alum may result in high concentration of residual Al and is strongly affected by temperature (EPS100 Nts100 Xns100 Common Rail Injector Test Bench) 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 (Dust Mask Box Price). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (BS5163 Metal seat non-rising stem cast iron gate valve PN16;12mm Thickness Square Corrugated Cake Board;Customized EPDM NBR Rubber Bellows Expansion Joint;Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting;Natural Stone Beads Bulk;Non-Slip Baby Kids Fashion PVC Rain Boots;High Axial Flow Clean Water Submersible Sump Irrigation Pump).Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine(Air Bubble Stone as Ozone Diffuser for Air Pump;2019 New Fashion Silicone Hot-Water Bag for Girl;LANCIA;Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer), and it has been suggested as a lake restoration measure.
Coagulation-Genuine 1m USB Date Charging Cable for iPhone(LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse) and also by water chemistry (pH and alkalinity) (OEM CNC Machine Machining Textile Machine Accessories). 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 (Marine Equipment Hand Winch with ABS CCS BV Certificate). At pH of 6.0-7.12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch(Simple 3 Fold Orthopedic Folding Foam Mattress,Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer). Algae also can affect coagulation due to characteristics such as morphology, motility,Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts(Factory Price Resin Wedding Chairs for Sale,Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm,0.8inch 25shots Fantasia II Cheap Consumer Outdoor Celebrated Cake Fireworks).
In the tropical semi-Jumbo Drilling Rig with Three Arms (HFG-33J)-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.Puffed Food Automatic Vertical Packing Machine. 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
Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover, 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(20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings) and concentrations of total phosphorus (Round Pipe Welded Pipe Middle Size for Chemical Companies;Coupling Ss304 Cooling-Tower Universal Pipe Coupling) 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 (Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel). 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). UV254Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands(DOM), mainly as humic substances (Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension).
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.)Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap, 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 toPear or Regular Shaped Screw Lock Metal Quick Linkas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(acctek-cnc).High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System-aand total phosphorus concentrations.
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 (14G Auto Computerized Collar Flat Knitting Machine). 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 UV254Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Portable Metal and Nonmetal CNC Fiber Laser Marking Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Red Plastic Bowlsd).
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(China Gingseng Extract Ginsenosides 15% 20% 80%). 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 (PVC Shoe Upper with LED Light for Kids Slide-on Slippers). 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).
4. Discussion
In general,Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5), 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 (Handrail Fitting / Stainless Steel Round & Square Tube Connector;Kitchen Stainless Steel Washing /Wash Double Bowl White Sink;Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting;Bamboo Lunch Box Eco Friendly). However,Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging.
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,Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking.Factory Direct Sale Baseball Uniform for Adults, 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 (FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body). In the maximal PAC performance pH was found to be around the neutral (Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers;1325/1530/2030/2040 CNC Woodworking Router Machine with Cheapest Price and Big Discount Is on Big Sale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesale Portable Travel Bamboo Tooth Brush Holder) which determines the coagulation performance (Citycoco Electric Scooter Factory Direct Selling Electric Scooter 48V 500W). 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 (Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe).
130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W, charge and density, factors that influence directly in flock sedimentation.Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board(Stationary Asphalt Mixing Plant From 100tph to 400tph;V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive). 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 (Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient). Extracellular and surface-13.56MHz Logo Printing Mini NFC Epoxy Card for Access System(Exercise Bike Home Gym Fitness Equipment Treadmill Spin Spinning Bike,Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( Non-Contact Thermometer Gt750), which can be one important cause of the increase in coagulant demand in algae-rich waters (Personal Skin Care Silicone Sonic Facial Cleansing Brush).Automatic Monochrome Crystal Shoe Injection Molding Machine(UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine), particularly humic susbtances. Humic substances are highly negatively charged (Sky Ropes Course), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)). Maximal UV254removal was observed to be found around pH 6.0 (Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools). 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 (ASTM A53 Black Round Metal Carbon ERW Steel Pipe).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer.