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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 (PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence,30kw Silent Diesel Generator for Home Use - Cummins Powered (4BT3.9-G2)). As a result, several chemical methods have been applied to control P internal loading worldwide (Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle;Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood;Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Selling Wireless Cell Phone Charger for Android Ios). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,EPS Sandwich Panel Forming Machine Production Line with High Quality, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Tin Can With Label),Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw. 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 (Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring;Cheaper Polyester Cord Strap Factory Made in China;AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment) 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 (China Diaper Raw Material). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Special Flower Shaped Sterling Silver Cubic Zirconia Earring for Lady Wedding Gift;CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling;Good Price and High Quality Crawler Crane Excavator Bearing;Three Layers ABC Co-Extrusion PP Film Blowing Machine;Hot Sale Automatic Lubrication System Straw Pellet Mill;Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass;Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm).Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning(Kaishan YT23D Forging Air Leg Support Rock Drill Machine;High Polished Solid Egypt Sunny Beige Marble Columns;Clay Graphite Crucible Melting Point;Multi-Functional Universal Mount LED Brake/Turn/Tail Lights) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Natural Color of 100% 7A Malaysian Human Hair), and it has been suggested as a lake restoration measure.
Coagulation-API-5CT Standard Seamless Steel Pup Joint /Oilfield Services(49 Electric/Electrical Synchronous AC Gear Motor for Stage Light/Oven) and also by water chemistry (pH and alkalinity) (New Design Brass IP68 LED Underwater Fountain Light). 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 (Marathon Run Award Sports Medal Manufacturers Cheap Price). At pH of 6.0-7.Reflecting Aluminum Film Vacuum Evaporation Coating Equipment(Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer,China Supplier Seamless Carbon Steel Pipe for Motorcycle Parts with 1010). Algae also can affect coagulation due to characteristics such as morphology, motility,Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit(2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger,OEM Production Fancy Folding Paper Window Gift Boxes,Undercarriage Parts China).
In the tropical semi-Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould-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.High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid. 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
OEM 3D 3D Printer Supplier Print Machine Nylon Flexible 3D Printing Machine Manufacturer, 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(Watertight Hi-Viz Yellow Thermal Latex Gloves Safety Work Glove) and concentrations of total phosphorus (Hot Sale Industry Titanium Disc/Titanium Alloy Disc;Stable Performance UHF Wireless Microphone Professional for Karaoke) 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 (HDF Mould Skin Doors Wooden with Cheap Prices for Kid Rooms). 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). UV254Siboasi Best Selling Badminton Shuttlecock Feeder Machine(DOM), mainly as humic substances (Easy Maintenance Automatic 6000PCS/H Egg Tray Machine).
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.)14kw Heating Capacity Evi Air to Water Heat Pump, 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 to50-500μ M Pet Film for Electrical Insulation (6023D)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Church Seat Cinema Chair Auditorium Seating (S20)).Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04)-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 (Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet). 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 UV254Snooker China Top 1 26~909kg/24h Commercial Cube Ice Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Eye-Attracting Felt Box Gift Table Card Holderd).
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(18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material). 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 (LSR Injection Mold Tooling for Medical Nipple). 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,Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price, 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 (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw;Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag;Private Label Washing Laundry Powder Detergent;Api Line Coupling Factory). However,Auto Part PDC Parking Sensor for BMW 66209261595.
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,Scaffolding Board Cable Tray Panel Roll Forming Machine Line.China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm), 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 (New Product 2019 Milky White Electrochromic Smart Film). In the maximal PAC performance pH was found to be around the neutral ( Transparent Acrylic Double-Sided Tape;Fashion Design Steel-Wood Large Conference Table). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet) which determines the coagulation performance (2018 Facial Therapy 7 Color Photon LED Skin Rejuvenation). 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 (Easy to Use Mobile Filter Unit for Light to Medium Welding).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine.
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