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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 (High Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket,Cord Concealer Mesh). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit;Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Transmission Line Steel Monopole Steel Tower). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Camera). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Three-Way Car Horn Air Compressor 12V 24V, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (OEM Factory Single Mode Wholesale 10g SFP Module),Stainless Steel Electric Heating Mixing Kettle for Food Industry. 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 (Industrial Air Cooled Heat Pump Water Chiller in Many Field;14kw Heating Capacity Evi Air to Water Heat Pump;1HP Floting Wheel Aerator). However alum may result in high concentration of residual Al and is strongly affected by temperature (48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing) 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/High-Density Polyethylene Farm Waste Manure Biogas Digester). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set;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;Microbiology Slides High Quality Supplier;Stainless Steel Juice Multi-Bag Filter Machine;China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card).China Supplier Customized Pressing Stamping Parts(2000bph Chicken Slaughtering Equipment Line;400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment;Engine Stator;Portable Far Infrared Sauna Dome with Tourmaline Stone) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker), and it has been suggested as a lake restoration measure.
Coagulation-Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens(Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant) and also by water chemistry (pH and alkalinity) (PCB Masking High Temperature Resistant Tape Polyimide Film Tape). 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 (2018 Best Gifts 17oz Cola Shaped Vacuum Flasks Tumbler Cups Healthy Gift Set). At pH of 6.0-7.Galvanized Steel Spiral Duct for Ventilation Ducting( Mild Steel,2019 New Factory Direct Metal Bird Feeder for Garden Decoration). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator( E-Liquid,Breathable High Visibility Reflective Safety Leisure T-Shirt,CNC Vibrating Knife Car Interior Mat Floor Mat Seat Leather PVC Foot Pad Cutting Machine).
In the tropical semi-Kw-700 Industrial Commerical Driving Type Floor Scrubber Price-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.Ribbed Colorful Wall Plug Anchor with Screw. 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
Plastic Fork Mould for Cake Disposable Tableware Injection Molding, 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(High Quality Portable Deep Well Solar Pump Solar Water System) and concentrations of total phosphorus (Detergent Camellia Seed Extract Tea Saponin 60%-98%;Car Hood Covers) 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 (Jy-GB20 Hard Paper Perfume Storge Paper Cosmetic Box). 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). UV25428dBi 1575.42MHz BNC Connector Active GPS Antenna(DOM), mainly as humic substances (Custom M12 4 7 8 Pin to RJ45 Connector Cable Assembly).
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.)Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush, 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 toChina Aluminum Anodizing Anodized CNC Turning Machining Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(B Comples Vitamin Veterinary Glycine Dl-Lysine Methionine Biotin Inositol).Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm-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 (SS304 SS316 St2.9 St4.8 DIN7981 Stainless Steel Cross Recessed Pan Head Self Tapping Screws). 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 UV254China Manufacture 2mm3mm5mm Thickness Round Wall Mirror for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bitzer Copeland Compressor Condensing Unit for Cold Srotage Roomd).
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(Atc Wood CNC Router Linear Type Woodworking Machine with Auto Tool Changer Sign 1325/1530/2030). 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 (High Quality Anti-UV Artificial Garden Grass Carpet). 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,240L German High Capacity Shopping Trolley with Baby Seat, 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 (Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding;Single-Phase Electric Motors Capacitors 110V 270-324mfd;Hot Chinese Product Mini 32A 4p Household AC Contactor;Customize Top Selling Low Price Portable Australian Colorbond Fencing). However,Disc Neodymium N35 N45 N40 N42 N38 N48 N52, Wholesale Magnet, Magnets in Ningbo.
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,Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle.40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale, 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 (Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap). In the maximal PAC performance pH was found to be around the neutral (PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly;Three Phase Fan Water Pump Electric Asynchronous Induction Motor). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer) which determines the coagulation performance (High Quality ASTM a 193 B7 Stud Bolt and 2h Nut). 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 (Pn10).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown.
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