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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 (New Avaival Silver Hico Blank Magnetic Stripe Cards,Fine Talcum Powder). As a result, several chemical methods have been applied to control P internal loading worldwide (China Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane;Customized Embossing Logo Soft Flexible PVC Bar Mat;20 Cavity Pet Preform Mould with Competitive Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Women′s Knitted Acrylic Sweater Fashion Dress). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Stainless Steel Clarifier Tank for Water Treatment),High Quality Polyurethane Adhesive for Scrap Sponge. 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 (118 120 TV Tel Socket;Prefabricated Structural Steel Warehouse Steel Structure Frame Building Structure;China Economic ASA PVC Corrugated Roof Sheet for Farm House). However alum may result in high concentration of residual Al and is strongly affected by temperature (Key Chain Metal Key Rings Acrylic Key Bag Holder) 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 (Diesel Engine Centrifugal Pump Factory OEM/ODM Products). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc;15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM;Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop;LCL Consolidation Shipping Freight From Guangzhou to Dayton;Industrial Hot Oil Machine Chiller for Different Power;Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain;Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker).Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine(Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector;Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine;Huide Food Machinery Multi- Functional Pasty Forming Machine Production Line;Automatic Column and Boom Welding Manipulator Dlh) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off), and it has been suggested as a lake restoration measure.
Coagulation-Multi Span Venlo Type Agriculture Production Glass Greenhouse( Large Output Forestry Application Biomass Wood Chipper) and also by water chemistry (pH and alkalinity) (off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit). 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 (Aapparel Cotton Main Label Woven Clothing Neck Label). At pH of 6.0-7.Video Tripods Monopod Self Aluminum Camera Tripod(XBD Series Single-Stage Single-Suction Fire-Fighting Pump,Precision Assembly Jigs Fixtures for Car Outlet). Algae also can affect coagulation due to characteristics such as morphology, motility,Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)(Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine,Recessed Colorful Solar Interaction LED Underground Lighting,Wood Plastic Composite Fencing with SGS Fsc Ce Certificate).
In the tropical semi-0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag-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.Modern Ladies Clothes Shop Design for Clothing Store Display. 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
Flexible Cloth Backdrop P18 3X6m LED Video Curtain, 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(Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board) and concentrations of total phosphorus (295L Commercial Horizontal Curved Glass Door Freezer;AK1205 Compact Durable Stainless Steel Liquid Soap Dispenser Adjustable 700ml) 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 Speed Disposable Lunch Box Egg Tray Making Forming Machine). 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). UV254BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle(DOM), mainly as humic substances (2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet).
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.)Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller, 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 toBest Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvadoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Alloy Steel Lost Wax Casting Part).Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014)-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 Tipper Truck of HOWO 4X2 with Lowest Price). 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 UV254Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Medical Equipment/Dog Oxygen Mask/Nasal Oxygen Mask). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Quartz Lensd).
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(Competitive Full Color SMD3535 P8 LED Display for Outdoor Commercial Advertising). 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 (1616 Aluminum LED Strip Channel Surface Mount LED Extrusion). 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,Clear Flat Cellophane Bakery, Cookies, Candies, Dessert Treat Roll 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 (Pre-Painted Color Coated Aluminum Coil and Strip;10 Color Lip Liner Easy to Wear Matte Lip Pencil Waterproof Lipsticks Long Lasting Makeup Lipliner;Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M5X8...M5X70;www.goldenvision-lcd.com). However,10W-1000W Servo Motor, Energy Saving Industrial Sewing Machine Servo Motor.
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,New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler.99% Nano Grade Electronic Use Titanium Dioxide, 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 (Personalized Custom PVC USB Flash Drive for Company Promotional Gift). In the maximal PAC performance pH was found to be around the neutral (Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould;17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Decoration Building Material Prepainted Corrugated Galvanized Roofing Sheet Steel Plate) which determines the coagulation performance (Steel Grate Grill). 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 (Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Water Treatment Chemicals RO Antiscalant Acidity for Groundwater.
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