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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 (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit,Exquisite Workmanship Six Player Carousel Kiddie Rides). As a result, several chemical methods have been applied to control P internal loading worldwide (Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Transmission Line Steel Monopole Steel Tower; Camera). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Industrial Air Cooled Heat Pump Water Chiller in Many Field). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fire Rated Decorative Internal HPL Laminated MGO Wall Board),High Quality Curve Spear Tunnel Bolt for Concrete Ring. 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 (14kw Heating Capacity Evi Air to Water Heat Pump;1HP Floting Wheel Aerator;48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set) 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 (HDPE Abalone Leisure Fishing Aquaculture Floating Circular Square Deep Sea Net Cage). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board;P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen;Automatic High Speed Welding Manipulator Machine;Stainless Steel Juice Multi-Bag Filter Machine;Auto Feeding Large Format Tailoring Laser Cutting Machine 1630/ 2050;China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card;2000bph Chicken Slaughtering Equipment Line).Flexional Soft Head Electronic Digital Thermometer(400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment;Portable Far Infrared Sauna Dome with Tourmaline Stone;Quality Powder Coating Machinery for Lawn Mower;30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant(PCB Masking High Temperature Resistant Tape Polyimide Film Tape) and also by water chemistry (pH and alkalinity) ( Mild Steel). 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 (Unique Design Ambulance Emergency First Aid Kit). At pH of 6.0-7.Top Quality Polar Wohlenberg Paper Cutting Blade(2019 New Factory Direct Metal Bird Feeder for Garden Decoration, E-Liquid). Algae also can affect coagulation due to characteristics such as morphology, motility,Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve(Breathable High Visibility Reflective Safety Leisure T-Shirt,Hot Sale Magnetic Strip Inserting Making Machine,China Golf Indicator).
In the tropical semi-1/2 Inch Soft Flexible Green Cloth Surface SAE 100 R3 Hydraulic Hose Rubber Hose-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.Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers. 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
Green&Health High Quality Modular Cold Room Storage for Fruits and Vegetable, 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(Detergent Camellia Seed Extract Tea Saponin 60%-98%) and concentrations of total phosphorus ( Made in China;Featured) 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 (Custom M12 4 7 8 Pin to RJ45 Connector Cable Assembly). 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). UV254Street Lighting 50W 100W 150W 200W LED Street Lamp Source Outdoor LED Street Light(DOM), mainly as humic substances (3 in 1 Flat Noodles Data Transfer Charger Cable for Android/Ios).
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.)7 Color LED Facial Mask Neck Mask LED Photon Mask for Skin Care, 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 toMagnetic Badge Holder Rectangle Magnet Button Badge Makeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Acrylic Led Light Up Coaster).Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches-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 (Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel). 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 UV2542016 500W Razor Crazy Electric Drift Trike for Adult%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stainless Steel Handrail Long Bar Holders for 12mm Pipe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Folding Biked).
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 Quality Anti-UV Artificial Garden Grass Carpet). 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 (Five Brushes Car Wash Rollover Car Washing Wholesale). 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,Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor, 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 (Single-Phase Electric Motors Capacitors 110V 270-324mfd;Hot Chinese Product Mini 32A 4p Household AC Contactor;Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap;ycycauto.com). However,Durable Soft Polishing Wheel for Polishing Wood and Plastic.
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,Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient.Wholesale RFID Paper Card Intelligent Smart Ticket for Subway or Park, 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 (PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly). In the maximal PAC performance pH was found to be around the neutral (Three Phase Fan Water Pump Electric Asynchronous Induction Motor;Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Pn10) which determines the coagulation performance (Industrial Low Watt Density Cartridge Heater with Thermocouple). 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 (Type S Pressure Reducing Valve for Food Processing).
RO Water Plant System Water Sediment Filter Machine, charge and density, factors that influence directly in flock sedimentation.CCTV 8.0MP 4K Video Security Surveillance IR Dome Ahd Camera(1.2344/AISI H13/JIS SKD61 Mould Steel for Die Casting; Drainage Pipe Machine). 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 (15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB). Extracellular and surface-Safety Belt Polyester for Lifting Sling /Round Sling (NHRS)(En74 Scaffolding Forged Double Couplers/Clamps/Fittings, Debossed Hotel Towel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Tamper Evident Walmart Office Depot White out Warning Void Self-Adhesive Security Tape for Bottle).Aluminum LED Outdoor Solar Lawn Light for Garden(American Type Earth Clamp for Welding Equipment), particularly humic susbtances. Humic substances are highly negatively charged (Plate Compactor Clutch), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Woodworking Edition - Waxed Canvas Tool Bag - Padded Straps). Maximal UV254removal was observed to be found around pH 6.0 (2017 New Material Fashion Luggage Good Suitcase). 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 (600W Lower Costs CO2 Laser Tube for Flat Die Board Laser Cutting Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Jinan Factory Atc Vacuum Table CNC Router with Cheap Price.
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