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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 (Carbon Steel Lifting Chain Eye Slip Hook with Latch ,m.laiya-jewelry.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe; Tail;Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Head Cap Disposable),24W RGB LED Outdoor Inground Light IP67 Deck Paver Lamp Spot Floor Light DMX512. 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 ( Cookies;7.5HP Centrifugal Circulation Swimming Pool Water Pump;90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage). However alum may result in high concentration of residual Al and is strongly affected by temperature (SMC / BMC Compression Molds and Molded Parts From China) 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 (High Basicity Polyaluminium Chloride PAC for Water Treatment). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine;2.5mm Ceramic Ball;Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids;Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes).China Supplier Fresh Milk Tank Delivery Truck for Farm Use(Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine;High Tolerance Stainless Steel Stamping Parts Enclosure;Lead Free Hot Air Reflow Oven;3 Inch Smooth Corrugated PVC Suction and Discharge Hose) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Electronic Wire Harness with Jst Molex Housing Connector), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings(Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip) and also by water chemistry (pH and alkalinity) (Factory Made Cheap Price Latching Circuit Relay for Power Control). 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 (Popular Size 48mm 90yard Adhesive Crystal Packing Tape). At pH of 6.0-7.100% Raw Material Micro Solid Carbide End Mills(Best Price 1325 Woodworking CNC Router Machine Equipment,100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers). Algae also can affect coagulation due to characteristics such as morphology, motility,Digital Universal High Power Ku Band Single LNB Price(High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller,6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure,Custom Made Sports Bra).
In the tropical semi-Red Color Garage Matting Rubber Sheet Flooring Manufacture in China-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.21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult. 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
China Automatic Round Stainless Steel Bar Peeling Lathe Machine, 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(Environmental Shot Peening Machine with Less Dust Emission) and concentrations of total phosphorus (Roll up High Quality Luxury Comfort Spring Mattress;Brass Two-Pole Floor Lamp Lighting/Light/LED/Decoration/Lamp) 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 (PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump). 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). UV254USB a to Lightning Quick Charge Data Cable(DOM), mainly as humic substances (Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor).
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.)Spot Supply Al2O3 85% Bauxite Use for Calcined, 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 toMobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Displayas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fuse Cutout).Portable Facial Skin Scrubber Scraper Machine for Beauty Care-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 (Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize). 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 UV254High Heat Resistant Silicone O Ring for Thermos/Bottle/Glass Jar%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Video Tripods Monopod Self Aluminum Camera Tripod). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (castironmariad).
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(New Avaival Silver Hico Blank Magnetic Stripe Cards). 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 (China Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane). 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,Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence, 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 (Women′s Knitted Acrylic Sweater Fashion Dress;118 120 TV Tel Socket;Prefabricated Structural Steel Warehouse Steel Structure Frame Building Structure;Electric Single Phase Fan Motor 220V 85W with Plastic Cooling Fan). However,Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize.
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,Factory Made Cheap Price Latching Circuit Relay for Power Control.High Elastic Nylon Breathable Arm Elbow Sleeve for Sports, 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 (China Economic ASA PVC Corrugated Roof Sheet for Farm House). In the maximal PAC performance pH was found to be around the neutral (Key Chain Metal Key Rings Acrylic Key Bag Holder;Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM) which determines the coagulation performance (m.ldkchina.com). 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 (Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop).
Ladies Fashion PU Leather Mini Backpack for Girles, charge and density, factors that influence directly in flock sedimentation.Factory Price Diesel Water Pump for Mine Dewatering(LCL Consolidation Shipping Freight From Guangzhou to Dayton;Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain). 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 (Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker). Extracellular and surface-Most Popular Android Satellite Receiver Android DVB S2 Cccam(Automatic Plastic Fork Spoon Knife Serviette Cutlery Packing Machine,Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Automatic Column and Boom Welding Manipulator Dlh).3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist(Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off), particularly humic susbtances. Humic substances are highly negatively charged (Good Ventilation Fully-Auto L-Bar Sealer Shrink Tunnel for Software), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( Large Output Forestry Application Biomass Wood Chipper). Maximal UV254removal was observed to be found around pH 6.0 (off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit). 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 (XBD Series Single-Stage Single-Suction Fire-Fighting Pump).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13.
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