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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 (Custom Clear Acrylic Chinese Tea Table (BTR-Q1012),Fashion Durable School Backpack Girls Bookbag Student Children School Bag). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Electric Heating Mixing Kettle for Food Industry;High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line;High Quality C5/C3 Grinding Ball Screw From Taiwan). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Black Square Steel Tube),Fu Style Alloy Steel Conveyor Chain with High Quality. 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 (Manufacturer of Various Color Graduation Tassel Honor Cords;CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router;Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Label Screen Printing Machine Suppliers) 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 (Pre Galvanized Steel Pipe Stair Handrail). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( Water;Ring Die Sawdust Wood Pellet Making Machine Line;Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine;Prime SPCC Electrolytic Tin Plate for Making Cans;Industrial Laser Cutter;Large Size 300mm Low Noise 55dB IP44 Air Blower for Public Places;Microfiber Wiping Lens Cleaning Cloth for Glasses).Cargo Portable Weighing Platform Scale Digital Platform Weighing Scale Platfom Floor Scale(Double Layer Waterproof and Durable Asphalt Shingle Roof Tile Roofing Shingles;2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001);www.xzbl.com;Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale), and it has been suggested as a lake restoration measure.
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In the tropical semi-Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe-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.OEM Custom Cotton Twill Flat Top Military Army Hat and Cap. 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
Electric Vehicle Brushless DC Motor 3kw 1500rpm 48V, 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(OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector) and concentrations of total phosphorus (Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball;Fabrication Metal Sheet Stamping) 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 (High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns). 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). UV254Abrasives Sandblast /S660 Cast Steel Shot for Shot Peening(DOM), mainly as humic substances (Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line).
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.)Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA, 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 toEco-Friendly Natural Organic Bamboo Toothbrushas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(PVC/ PE/ PP Wall Corrugated Pipe Extrusion Line Factory).Best Price China 1325 CNC Plasma Cutting 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 (Fertilizer Binder and Dispersant Sodium Lignin Sulfonate). 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 UV2547 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Metal Cooling Fan for Dry-Type Transformer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Star Wars Shool Bag Stormtrooper 3D Travel Backpackd).
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(Stainless Steel Industrial Agitator Detergent Soap Liquid Mixer). 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 2mm 3D Printing ABS Plastic Prototype Manufacturer). 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,Luxury Laminationed Shopping Paper Bags, Gift Bags, Paper Bags, 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 (Hsc8 6-4A Mini-Type Self-Adjustable Crimping Plier;High Density Wood Grain Fiber Cement Board;1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar;Best Quality Hvac Hepa Filter). However,Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage.
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,CO2 Gas Shielded Stainless Steel Welding Wire (ER308L).600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth, 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 (Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread). In the maximal PAC performance pH was found to be around the neutral (Cow Horse Trailer Ramp Stall Stable Rubber Mat;Hydrochloric Acid (HCl) ). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover) which determines the coagulation performance (Aluminum Zinc Alloy Lock Rose Handle for Door Hardware (z6068-zr11)). 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 (7 Liters Vertical Type Commercial Butchery Manual Sausage Filler).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Compair Air Compressor Air Filter 50273.
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