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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 (Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump,Anti Fog Safety Goggles). As a result, several chemical methods have been applied to control P internal loading worldwide (Permanent Magnetic Separator for Conveyor Belts;High Quality HVAC Exhaust or Supply Plastic Air Valve;High Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Dryer Machine Specially),21cm Width 5m Length Self Adhesive Seaming Tape for Artificial Turf. 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 (Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Transmission Line Steel Monopole Steel Tower; Camera). However alum may result in high concentration of residual Al and is strongly affected by temperature (Industrial Air Cooled Heat Pump Water Chiller in Many Field) 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 (304 Decorative Stainless Steel Sheet with Color). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set;100% Polyester 400t Taffeta Fabric for Lining/Garment Fabric;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).Made in China Multi-Storey Steel Structure with Light Steel Frame(Automatic High Speed Welding Manipulator Machine;Stainless Steel Juice Multi-Bag Filter Machine;1000*2000 1200*2400mm PP Corflute Coroplast Correx Display/Signage Board / Printing for UAE Market;China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2000bph Chicken Slaughtering Equipment Line), and it has been suggested as a lake restoration measure.
Coagulation-3D Touched PU Faux Artificial Embroidery PVC Leather for Wall, Door, Sofa, Chair, Sofa(400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment) and also by water chemistry (pH and alkalinity) (Portable Far Infrared Sauna Dome with Tourmaline Stone). 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 (nbzkls). At pH of 6.0-7.Promotion 100%Cotton Baseball Cap Manufacturer Export to Europe(30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker,Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant). Algae also can affect coagulation due to characteristics such as morphology, motility,Provide Low-Volume Production Injection Moulding(PCB Masking High Temperature Resistant Tape Polyimide Film Tape, Mild Steel,Dn50 Long Distance Rain Gun for Farm Irrigation).
In the tropical semi-Food Machine/Chd330 Compact Carrot Cutter Cutting Machine-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.Modern Style Classic Shangri-La Window Shutters Roller Blinds. 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
Custom Industrial Field Block Ferrite Rare Earth Magnet, 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(Breathable High Visibility Reflective Safety Leisure T-Shirt) and concentrations of total phosphorus (Hot Sale Magnetic Strip Inserting Making Machine;China Laptop Adapter 19v) 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 (Detergent Camellia Seed Extract Tea Saponin 60%-98%). 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). UV254Factory Direct Sale Warehouse Light IP65 150W LED High Bay(DOM), mainly as humic substances ( Made in China).
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.)Custom Label Printed Black Matte Smell Proof Aluminum Foil Ziplock Zipper Bags, 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 to3 in 1 Flat Noodles Data Transfer Charger Cable for Android/Iosas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(jb-hardware).Twist Lock Power Cord, Twist Lock Power Cable-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 (China Aluminum Anodizing Anodized CNC Turning Machining Parts). 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 UV254Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Magnetic Badge Holder Rectangle Magnet Button Badge Maker). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Large Damping Compression Spring for Industrial Machinery (10*89*177*7.5)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(SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws). 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 (Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel). 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,Brc Welded Wire Mesh Fence/3D Curvy Welded Wire Mesh Fence, 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 (High Quality Anti-UV Artificial Garden Grass Carpet;Five Brushes Car Wash Rollover Car Washing Wholesale;Vegetarian/Vacant/Pharmaceutical/Hard/HPMC/Pullulan/Gelatin/Size000/Empty Capsules;Flat Plastic Roofing). However,Medical Infusion Pump for Human and Veterinary with Fluid Warmer.
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,Kinkai Meat Heat Pump Dryer Machine/ Drying Oven.Men′s Watch High Quality Steel Quartz Wrist Watch (72057), 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 (Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding). In the maximal PAC performance pH was found to be around the neutral (Single-Phase Electric Motors Capacitors 110V 270-324mfd;Hot Chinese Product Mini 32A 4p Household AC Contactor). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap) which determines the coagulation performance (Large Aluminum Coated Mirror Hang on Wall). 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 (PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale Chinese Sax / Tenor Saxophone, High Quality, Made in China.
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