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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 (Pure Hyaluronic Acid Powder with Reasonable Price,Strong Adhesive Custom Invisible Logo Clear Packing Tape). As a result, several chemical methods have been applied to control P internal loading worldwide (3D Finish Soundproof Movable Partition Wall for Meeting Room;Factory Standard Low Pressure Wafer Butterfly Valve Pn10;Water Cooled Vibrating Grate Boiler for Power Plant EPC). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Non-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodes). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Micro Inch Finishes for High Precision Grinding Lapping Metal Non-Metal Part, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Top Quality Tungsten Carbide Inserts for Turning Milling CNC PCD CBN),Classic Cafe Dining Chair with High Quality/Grey/Arm Chair. 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 (Lovol Rice Combine Harvester-Small Tank with Two Hoppers;Food Grade Oval Cute Newborn Pacifiers with Soft Soother;Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump). However alum may result in high concentration of residual Al and is strongly affected by temperature (Permanent Magnetic Separator for Conveyor Belts) 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 (SGCC Galvalume Aluzic Steel Coil Gl Steel for Roofing Sheet). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality HVAC Exhaust or Supply Plastic Air Valve;High Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket;Customized Stainless Steel Cut Wire Shots Sand Blasting Grit;Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Baby Safety Products;Transmission Line Steel Monopole Steel Tower; Camera).Electroplated Diamond 200mm Circular Saw Blade for Concrete Cutting(Industrial Air Cooled Heat Pump Water Chiller in Many Field;14kw Heating Capacity Evi Air to Water Heat Pump;Casting Steel Grinding Resistant Ball Supplier & Manufacturer;1HP Floting Wheel Aerator) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing), and it has been suggested as a lake restoration measure.
Coagulation-Solid State Relay, SSR -40va, Ce Proved Solid State Relay, 24-380VAC Single Solid State Relay(Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set) and also by water chemistry (pH and alkalinity) (Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board). 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 (Industrial Mini Electricity Portable Screw Air Compressor). At pH of 6.0-7.Best Custom Private Label Glass Pillar Paraffin Votive Birthday Flameless Scented Candle with Jar(P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen,Automatic High Speed Welding Manipulator Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem(Stainless Steel Juice Multi-Bag Filter Machine,China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card,Sodium Hydroxide Tank Semi-Trailer 3 Axles 20000liters).
In the tropical semi-Factory Wholesale T5 T6 7075 6061 6063 Alloy Aluminium/Aluminum Sheet Plate-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.LG Innotek Drt 3.0 42 a + B, LG 42 Lb a+B Square, 42′ LG LED TV Backlight Lens Strips/Bars/Spears. 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
Precision CNC Machined Part Aluminum Stainless Steel Components, 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(Portable Far Infrared Sauna Dome with Tourmaline Stone) and concentrations of total phosphorus (30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker;Square Cooling Tower) 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 ( Mild 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). UV254Yx35-925 Glazed Tile Roll Forming Making Machine(DOM), mainly as humic substances (2019 New Factory Direct Metal Bird Feeder for Garden Decoration).
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.)100% Virgin Material PMMA Cast Acrylic Sign Board, 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 toDenso Nozzle G3s32 for 295050-056#1465A351 Common Rail Injector Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Pressure Above Ground Swimming Pool Electric 380V Water Pumps).Good Performance High Precision Thrust Roller Bearing (29292)-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 ( Made in China). 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 UV254Good Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ce Factory Sale Waste Logs Drum Wood Chipper). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Stripes Polyester Mens Classical Fashion Necktied).
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(Custom M12 4 7 8 Pin to RJ45 Connector Cable Assembly). 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 (3 in 1 Flat Noodles Data Transfer Charger Cable for Android/Ios). 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,HR/CR/GI High Frequency Longitudinal Seam Tube Mill, 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 (China Aluminum Anodizing Anodized CNC Turning Machining Parts;Magnetic Badge Holder Rectangle Magnet Button Badge Maker;Wholesale Wooden Inlay Shell Custom Boutique Comb;2.4g Wireless Sync Dimmer). However,Wisdom Brand Top Quality LED Mining Safety Lamp, Miner Lamp.
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,Extrusion Mould Cemented Tungsten Carbide Wire Drawing Die.Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener, 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 (SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws). In the maximal PAC performance pH was found to be around the neutral (Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel;Stainless Steel Handrail Long Bar Holders for 12mm Pipe). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Atc Wood CNC Router Linear Type Woodworking Machine with Auto Tool Changer Sign 1325/1530/2030) which determines the coagulation performance (Car Parts Mazda 6 Cabin Filter Active Carbon Air Filter Gj6a-61-P11A Gj6a-61-P11). 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 Quality Anti-UV Artificial Garden Grass Carpet).
Corn Starch Foam Biodegradable Frozen Food Packaging Tray, charge and density, factors that influence directly in flock sedimentation.Highway Outdoor Road Integrated Solar LED Street Light Price List(Five Brushes Car Wash Rollover Car Washing Wholesale;Vegetarian/Vacant/Pharmaceutical/Hard/HPMC/Pullulan/Gelatin/Size000/Empty Capsules). 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 (Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding). Extracellular and surface-Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V(Autamatic Feeding Cutting Machine,Single-Phase Electric Motors Capacitors 110V 270-324mfd). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Hot Chinese Product Mini 32A 4p Household AC Contactor), which can be one important cause of the increase in coagulant demand in algae-rich waters (Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap).Integrated Circuit Printed Circuit Board China Trusted PCB Manufacturer(PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly), particularly humic susbtances. Humic substances are highly negatively charged (Cjx9 Seires Air Condition Definite Purpose AC Magnetic Contactor), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Three Phase Fan Water Pump Electric Asynchronous Induction Motor). Maximal UV254removal was observed to be found around pH 6.0 (Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer). 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 (Pn10).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale Comfortable Men′s Winter Leather Snow Boots.
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