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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 (Anon Philippines Hot Selling 4lz-2.5 Mini Rice Wheat Combine Harvester,12V/24V Car Charger with DC Cable and Switch). As a result, several chemical methods have been applied to control P internal loading worldwide (AC Magnetic Contactorstc-40 (GMC) Electric Contactor;Good Price Automatic Kitchen Towel Tissue Paper Rewinding Machine;20FT Double Axle Skeletal Port Trailer Container Semi Trailer Chassis). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Factory Produced 40X40mm Pre Galvanized Square Welded Steel Pipe),Eco Friendly Kraft Biodegradable 5ml Bamboo Lip Balm Tubes Lipstick Tube. 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 (Dn630mm Plastic Pipe Butt Fusion Welding Machine;Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps;Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley). However alum may result in high concentration of residual Al and is strongly affected by temperature (12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools) 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 (Home Hydroponic Systems). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home;Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat;Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service;Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price;Professional Metal Pipe Cutting Tools P2060;3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker;Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill).Uncoated Test Liner Fluting Medium Paper for Box Packaging(Agriculture Cultivator Springs Double Spring Tines 3.5-12mm;Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip;Stainless Sheet Carbon Sheet Plasma Cutting Machine / Metal Plasma Cutter;Wholesale High Quality USB Charging Data Cable for Original Apple iPhone 7 Charger Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module), and it has been suggested as a lake restoration measure.
Coagulation-Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price(Long Service Life Smooth Lead Screw Tr3.5X0.61) and also by water chemistry (pH and alkalinity) (Computerized CNC Turning Machine Metal Lathe Price Ck63L). 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 (Commercial Electric Taiwan Snow Ice Shaver Machine). At pH of 6.0-7.High Density Multi-Layer PCB Prototype PCB Printed Circuit Board Professional Manufacturer(8mm PVC Coated Galvanized Steel Wire Rope for Lifting,Manufacture RP HP UHP Graphite Electrode 300mm 350 with Nipples for Smlting). Algae also can affect coagulation due to characteristics such as morphology, motility,2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch(Good Quality UPS Batteries 12V 65ah for Burglary Protection System,Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration,Imidacloprid 350 Sc).
In the tropical semi-Low Price & High Quality Stainless Steel X-ray Lead Door-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.Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt. 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
High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals, 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 Fan 3 in 1-Competitive Price) and concentrations of total phosphorus (CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine;OEM High Flow Centrifugal Sand Pump/Dredging Mud Pump with Ce Approved) 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 (Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition). 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). UV254Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor(DOM), mainly as humic substances ((Made in China gold sellers) SPA Swimming Pool Water Filter Pump).
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.)PVC Stripe Anti-Slip Door Mat with Color Logo, 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 toGondola Supermarket Shelf Candy Shelf for Confectionery Equipmentas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(10000 Psi Hydraulic Fittings).Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant-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 (Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)). 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 UV254Personal Skin Care Silicone Sonic Facial Cleansing Brush%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Big Suction Power Cordless Vacuum Cleaner (WSD1801-21)d).
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(Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack). 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 (Disposable Plastic PE Icing Piping Cake Decorating Pastry Bag Making Machine). 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,Environmental Shot Peening Machine with Less Dust Emission, Model: Mrt2-80L2-4, 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 (4-20mA Signal Steam Directional Flow Pneumatic Control Valve;Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow;Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery;Eps Corner Machine). However,Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass 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,19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen.Live Broadcast Camera 4K 3840X2160 Ultra HD IPS LCD Screen 17.3 LCD Display, 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 (Automatic CNC Pipe Beveling Machine with Three Servo Motor (TEF508CPV)). In the maximal PAC performance pH was found to be around the neutral (Ddsafety 2018 Safety Wholesale Nitrile Coating Protective Cut Resistant Glove;New Addition and Cheap Frame Upward 4 Column Hydraulic Press). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Br42 Red Color Mushroom Head Push Button Switches) which determines the coagulation performance (Fiberglass Animals For Sale). 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 (High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design).
Organic Waste Gas Treatment Device Gas Disposal on Hot Sale, charge and density, factors that influence directly in flock sedimentation.Non-Slip Baby Kids Fashion PVC Rain Boots(Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light;Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing). 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 (Multilayer 6-Layer Green Mask Immersion. Gold PCB). Extracellular and surface-Heavy Duty Double Ladder Trailer Top Tent(2 Sides Cat Eyes Road Stud,Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Stainless Steel Plate Frame Customized Sheet Metal Processing Laser Cutting), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Quality Folding Us Plug 5V 1A USB Travel Charger).Ductile Iron Service Gate Valve Ductile Iron Screwed Ends Resilient Gate Valve Thread(Easy Fan Lashes Blooming Lashes Volume Eyelashes Extension), particularly humic susbtances. Humic substances are highly negatively charged (93 Oxygen Saturation), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Single Phase Frequency Inverter AC Motor Speed Controller 250000W). Maximal UV254removal was observed to be found around pH 6.0 (Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market). 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 (Dienedione Raw Powder Estra-4).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time.
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