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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 Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant,cnvegeprotein.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Eco Brava Small Mud Interlock Brick Press Machine;7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing;Textile Machine Parts Multiple Pattern Box). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Irrigation Water Pump),Cee/IEC 32A 5p 400V 3 Phase European Standard Plug. 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 (Accept Customization Perfume Direct with Good Price;AAC Autoclaved Aerated Concrete Brick Making Machine;Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter). However alum may result in high concentration of residual Al and is strongly affected by temperature (Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette) 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 (Industrial Removing Green Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound;Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair;2400 Dpi Resolution Offline CTP Offset Printer;Trailer Part Coupling;Custom Made Commercial Good Quality Hotel Bedroom Furniture Set Hotel Headboard;Small MOQ Food Grade Glass Bottle Wine Cork Stopper;High Quality Precision Plastic Mold/Mould Insert).Induction Heater Electric High Temperature Furnace for Casting(Alternator for Toyota 91;Guard Rail Roll Forming Machine 2.0-4.0mm Thickness;Original Japan Used Caterpillar 950e Wheel Loader (CAT 950 Loader);China Genuine Leather White Color Safety Shoes) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (HS20-600 Shipping Lifting Device Customized Hydraulic Station), and it has been suggested as a lake restoration measure.
Coagulation-300W 600W Solar Submersible Deep Well Pumps, Solar Water Pump for Garden Irrigation (SC Series)(China Supplier Customized Polish Storage Wall Mounted Wine Rack) and also by water chemistry (pH and alkalinity) (Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use). 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 (Waste Water Treatment Centrifugal Chemical Pump). At pH of 6.0-7.Sbm Best Sales Vertical Milling Machine, Limestone Roller Mill(Zp9 Punches and Dies Rotary Tablet Press for USA Market,Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press). Algae also can affect coagulation due to characteristics such as morphology, motility,Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk(Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel,Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863,Floor Abrasion Test Machine).
In the tropical semi-Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line-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.Used Fashion Summer Children′s Dress Unsorted. 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 Aluminum Housing with Anodizing Color, Aluminum Enclosure for LED, 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(Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car) and concentrations of total phosphorus (Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag;0.5mm Thickness Mill Finish 1050 Alloy Aluminum Coil for Construction) 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 (Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd). 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). UV254Bolts and Nuts Set Brass Fasteners Double Hex Bolt(DOM), mainly as humic substances (60 Ton Track Material Handling Excavator for Sale).
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.)Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment, 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 toDn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valveas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Cable Puller).Hot Selling Round Cookware Pan with Induction Bottom Frying Pan-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 (TUV Standard China Jump Park Free Jumping Bounce Bed Trampoline Park for Kids). 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 UV254Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hot Sale Glass Manual Salt Grinder Pepper Mills/Spice Jars). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Sanitary Fittingd).
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(LED Display Fixed Co Gas Monitor Toxic Gases Analyzing). 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 (Rare Earth Metal Material Cerium Target for Magnetron Sputtering System). 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,CNC Turning Stainless Steel Part with Precision Tolerance, 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 (Composite Suspension Transmission Insulator String with Electrical Power Fitting;SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker;Aluminum DJ Truss for Exhibition Lighting Truss;Medical Facial Contour Filler Injectable Hyaluronic Acid Gel Injection Dermal Filler). However,Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal 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,Fashion Double Striped Non-Slip Entrance Mat.145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe, 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 (Biodegradable PLA Film for Food /Fruit Packaging). In the maximal PAC performance pH was found to be around the neutral (Automatic Paver Block Making Machine for Sale;12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Outdoor Body-Building Sitting Device for Improving Stability of Lower Limbs) which determines the coagulation performance (Dentist Chairs Controlled Integral Dental Clinic Equipment). 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 (Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Pressure Rubber Hydraulic Hose Assembly.
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