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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 (Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper,8 Ton Truck Crane). As a result, several chemical methods have been applied to control P internal loading worldwide ( Cookies;7.5HP Centrifugal Circulation Swimming Pool Water Pump;90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (SMC / BMC Compression Molds and Molded Parts From China). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ce Certificate 24-Port Cat 6 Shielded Patch Panel, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Best selling item),Smoking Ceramic Pods Empty Cartridge Start Kit. 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 (800g ECR Glass Fibre Plain Woven Roving 800GSM for Munal Boats Buildings;High Quality Low Price Square Pipe CNC Plasma Cutting Tool;USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine) 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 (Bags Manufacturer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids;Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes;Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine;High Tolerance Stainless Steel Stamping Parts Enclosure;Kids 50cc Bike;3 Inch Smooth Corrugated PVC Suction and Discharge Hose;Custom Electronic Wire Harness with Jst Molex Housing Connector).EPS Sandwich Panel Forming Machine Production Line with High Quality(Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip;Factory Made Cheap Price Latching Circuit Relay for Power Control;7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing;Best Price 1325 Woodworking CNC Router Machine Equipment) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers), and it has been suggested as a lake restoration measure.
Coagulation-Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw(High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller) and also by water chemistry (pH and alkalinity) (6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure). 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 (20 Mil Lvt Lvp Spc Luxury Vinyl Plank Flooring for Household). At pH of 6.0-7.Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning(HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas,Touch Screen Display Module Control Panel for Instrument). Algae also can affect coagulation due to characteristics such as morphology, motility,API-5CT Standard Seamless Steel Pup Joint /Oilfield Services(Environmental Shot Peening Machine with Less Dust Emission,Roll up High Quality Luxury Comfort Spring Mattress,Wholesale Bicycle Inner Tube 24X1.95 26X2.125 700c).
In the tropical semi-Reflecting Aluminum Film Vacuum Evaporation Coating Equipment-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.Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit. 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
Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould, 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(PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump) and concentrations of total phosphorus (Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor;Carbon Laminated Scrims Fabric For Building) 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 (Ce Approved Acrylic Mini LED Letters Sign for Outdoor). 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). UV254High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid(DOM), mainly as humic substances (Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display).
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.)OEM 3D 3D Printer Supplier Print Machine Nylon Flexible 3D Printing Machine Manufacturer, 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 toVideo Tripods Monopod Self Aluminum Camera Tripodas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Siemens 00322592-04 SMT Pick up Nozzle 738 938 Nozzle Original New or Copy New).Siboasi Best Selling Badminton Shuttlecock Feeder Machine-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 Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane). 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 UV25414kw Heating Capacity Evi Air to Water Heat Pump%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Embossing Logo Soft Flexible PVC Bar Mat). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Men Makeup Cosmetic Bag Supplier & Factoryd).
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(Women′s Knitted Acrylic Sweater Fashion Dress). 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 (118 120 TV Tel Socket). 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,Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04), 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 (Key Chain Metal Key Rings Acrylic Key Bag Holder;Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc;15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM;Hawthorn Fruit Extract). However,Snooker China Top 1 26~909kg/24h Commercial Cube Ice 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,Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price.Auto Part PDC Parking Sensor for BMW 66209261595, 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 (Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop). In the maximal PAC performance pH was found to be around the neutral (LCL Consolidation Shipping Freight From Guangzhou to Dayton;Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker) which determines the coagulation performance (Cold Rolled Zinc Coated Galvanized Steel Coil Z80g). 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 (Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector).
Scaffolding Board Cable Tray Panel Roll Forming Machine Line, charge and density, factors that influence directly in flock sedimentation.China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm)(Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine;Automatic Column and Boom Welding Manipulator Dlh). 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 (Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off). Extracellular and surface-Woodworking Edition - Waxed Canvas Tool Bag - Padded Straps(Stainless steel tensile parts, Large Output Forestry Application Biomass Wood Chipper). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit), which can be one important cause of the increase in coagulant demand in algae-rich waters (XBD Series Single-Stage Single-Suction Fire-Fighting Pump).Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter(Precision Assembly Jigs Fixtures for Car Outlet), particularly humic susbtances. Humic substances are highly negatively charged (Acrylic Paint Bottle Set Supplier), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine). Maximal UV254removal was observed to be found around pH 6.0 (Recessed Colorful Solar Interaction LED Underground Lighting). 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 (Factory Custom Rubber Badge PVC Patches with Male Velcro).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Six Spout Impeller Cement Packing Machine.
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