scholarly journals Transformation Kinetics of Burnt Lime in Freshwater and Sea Water

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4926
Author(s):  
Harald Justnes ◽  
Carlos Escudero-Oñate ◽  
Øyvind Aaberg Garmo ◽  
Martin Mengede
Keyword(s):  
Calcium Hydroxide ◽  
Magnesium Hydroxide ◽  
Open System ◽  
Algal Blooms ◽  
Sea Water ◽  
Negative Impact ◽  
Particle Surface ◽  
Burnt Lime ◽  
Green Algal ◽  
Kinetics Of

Calcium oxide (CaO), also known as burnt lime, is being considered as a possible treatment to reduce the negative impact of sea urchins on tare forests in northern coastal waters and blue-green algal blooms in the surrounding of fish-farms. In this respect, the reaction kinetics of burnt lime in contact with sea water has been elucidated and compared to its behaviour in fresh water. In the first minutes of contact between burnt lime and water, it “slaked” as CaO reacted with water to yield calcium hydroxide (Ca(OH)2). Subsequently, calcium hydroxide reacted with magnesium, sulphate and carbonate from the sea water to yield magnesium hydroxide (Mg(OH)2), calcium sulphate dihydrate (gypsum, CaSO4·2H2O) and calcium carbonate (CaCO3), respectively. In a closed system of 1% CaO in natural sea water (where the supply of sulphate, magnesium and carbonate is limited), more than 90% reacted within the first 5 h. It is foreseen that in an open system, like a marine fjord, it will react even faster. The pH 8 of sea water close to the CaO particle surface will immediately increase to a theoretical value of about 12.5 but will, in an open system with large excess of sea water, rapidly fall back to pH 10.5 being equilibrium pH of magnesium hydroxide. This is further reduced to <9 due to the common ion effect of dissolved magnesium in sea water and then be diluted to the sea water background pH, about 8. Field test dosing CaO particles to sea water showed that the pH of water between the particles stayed around 8.

scholarly journals Transformation Kinetics of Burnt Lime in Freshwater and Sea Water

2020 ◽  
Author(s):  
Harald Justnes ◽  
Carlos Escudero-Oñate ◽  
Øyvind Aaberg Garmo ◽  
Martin Mengede
Keyword(s):  
Calcium Hydroxide ◽  
Magnesium Hydroxide ◽  
Open System ◽  
Sea Water ◽  
Particle Surface ◽  
Calcium Sulphate ◽  
Burnt Lime ◽  
Common Ion ◽  
The Common ◽  
Kinetics Of

The reaction kinetics of burnt lime (CaO) in contact with sea water has been elucidated and compared to its behaviour in fresh water. In the first minutes of contact between burnt lime and water, it "slaked" as CaO reacted with water to yield calcium hydroxide (Ca(OH)2). Subsequently, calcium hydroxide reacted with magnesium, sulphate and carbonate from the sea water to yield magnesium hydroxide (Mg(OH)2), calcium sulphate dihydrate (gypsum, CaSO4&middot;2H2O) and calcium carbonate (CaCO3), respectively. In a closed system of 1% CaO in natural sea water (where the supply of sulphate, magnesium and carbonate is limited), more than 90% reacted within the first 5 hours. It is foreseen that in an open system, like a marine fjord, it will react even faster. The pH 8 of sea water close to the CaO particle surface will immediately increase to a theoretical value of about 12.5 but will, in an open system with large excess of sea water, rapidly fall back to pH 10.5 being equilibrium pH of magnesium hydroxide. This is further reduced to &lt; 9 due to the common ion effect of dissolved magnesium in sea water and then be diluted to the sea water background pH, about 8. Field test dosing CaO particles to sea water showed that the pH of water between the particles stayed around 8.

scholarly journals The algae community in taxon Haptophyceae at the early bloom stage of Phaeocystis globosa in Northern Beibu Gulf in winter

2018 ◽  
Author(s):  
Bin Gong ◽  
Haiping Wu ◽  
Jixian Ma ◽  
Meimiao Luo ◽  
Xin Li ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Algal Blooms ◽  
Sea Water ◽  
Regression Coefficient ◽  
Negative Impact ◽  
Linear Regression Analysis ◽  
River Estuary ◽  
Beibu Gulf ◽  
Red Tides ◽  
Phaeocystis Globosa

Phaeocystis globosa (Order Phaeocystales, family Phaeocystaceae) caused significant impact on aquaculture farming, global climate change and industry. Since the year 2010, intensive red tides of P. globosa began to appear in Beibu Gulf, where previously free of harmful algal blooms, and posed great threats to the cooling systems of a nuclear power plant in 2014 and 2015. In order to discover the bloom mechanism, the community structure of marine microalgae, with a focus on Haptophyceae taxa, in winter in the northern Beibu Gulf near the Qinzhou Bay, Sanniang Bay (SNB) and Dafenjiang River Estuary (DRE), were explored via 18S ribosomal DNA analysis of the V4 region using the Illumina-Based Sequencing platform. The correlation between the relative abundance of five kinds of Haptophyceae algae and environmental factors of seawater were analyzed. The most abundant Haptophyceae-related OTU in terms of number of reads was identified as Phaeocystis and Chrysochromulina. The abundance for other Haptophyceae class was relatively low, such as Haptolina, Prymnesium and Isochrysis. Phaeocystis was present in all samples sites except S6, S11, S12, S14 and S15, and particularly abundant at S8, nearly 29 times more than the second most abundant site. Most notably, the results showed that Phaeocystis displayed highly positive linear correlation with the concentration of NO3--N (Pearson r=0.856, p<0.01). Linear regression analysis indicated that Phaeocystis was significantly linearly related to the NO3--N (R2=0.732; Y=-0.005 + 0.410*X, Y is the relative abundance of P.globosa, X is the concentration of NO3--N; F=38.227, P<0.05) and NO3--N has a significant positive effect on P.globosa (regression coefficient is 0.410, P=0.000). Moreover, the relative abundance of Phaeocystis was significant related to temperature of sea water (Pearson r=-0.882,p<0.01). Water temperature can explain the 77.8% change reason for the P.globosa (R2=0.778), and has a significant effect on P. globosa (Y=0.169-0.009*X, F=49.031,P<0.05), and the regression coefficient is -0.009 (P=0.000) which indicated a significant negative impact relationship between them. Our high throughput sequencing (HTS) based research illustrated how the P. globosa bloom generated and its relationship with NO3--N and temperature of sea water in northern Beibu Gulf for the first time, and bringing hope for solving this big problem.

Phosphorus removal by apatite in horizontal flow constructed wetlands for small communities: pilot and full-scale evidence

2011 ◽  
Vol 63 (8) ◽  
pp. 1629-1637 ◽  
Author(s):  
N. Harouiya ◽  
S. Martin Rue ◽  
S. Prost-Boucle ◽  
A. Liénar ◽  
D. Esser ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Particle Surface ◽  
Full Scale ◽  
Retention Capacity ◽  
Small Communities ◽  
Lab Experiments ◽  
Apatite Mineral ◽  
Kinetics Of ◽  
P Removal

Phosphorus (P) removals in constructed wetlands (CWs) have received particular attention in recent decades by using specific materials which promote adsorption/precipitation mechanisms. Recent studies have shown interest in using apatite materials to promote P precipitation onto the particle surface. As previous trials were mainly done by lab experiments, this present study aims to evaluate the real potential of apatites to remove P from wastewater in pilot units and a full-scale plant over a 2 year period. P retention kinetics of two qualities of apatites are presented and discussed. In this work apatite appears to have high retention capacity (&gt;80% of P removal) and is still an interesting way for P removal in CWs for limiting the risk of eutrophication downstream of small communities. Nevertheless, the apatite quality appears to be of great importance for a reliable and long term P removal. The use of materials with low content of apatite mineral (40–50%) seems to be not economically relevant.

scholarly journals THE KINETICS OF PENETRATION

1937 ◽  
Vol 20 (5) ◽  
pp. 737-766 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Sea Water ◽  
Surface Layers ◽  
Marked Contrast ◽  
External Concentration ◽  
Protoplasmic Surface ◽  
Kinetics Of ◽  
External Ph

When 0.1 M NaI is added to the sea water surrounding Valonia iodide appears in the sap, presumably entering as NaI, KI, and HI. As the rate of entrance is not affected by changes in the external pH we conclude that the rate of entrance of HI is negligible in comparison with that of NaI, whose concentration is about 107 times that of HI (the entrance of KI may be neglected for reasons stated). This is in marked contrast with the behavior of sulfide which enters chiefly as H2S. It would seem that permeability to H2S is enormously greater than to Na2S. Similar considerations apply to CO2. In this respect the situation differs greatly from that found with iodide. NaI enters because its activity is greater outside than inside so that no energy need be supplied by the cell. The rate of entrance (i.e. the amount of iodide entering the sap in a given time) is proportional to the external concentration of iodide, or to the external product [N+]o [I-lo, after a certain external concentration of iodide has been reached. At lower concentrations the rate is relatively rapid. The reasons for this are discussed. The rate of passage of NaI through protoplasm is about a million times slower than through water. As the protoplasm is mostly water we may suppose that the delay is due chiefly to the non-aqueous protoplasmic surface layers. It would seem that these must be more than one molecule thick to bring this about. There is no great difference between the rate of entrance in the dark and in the light.

The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 97-110
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Narrow Range ◽  
Saline Water ◽  
Fluid Secretion ◽  
Osmotic Concentration ◽  
Drinking Rate ◽  
Aedes Taeniorhynchus ◽  
External Salinity ◽  
Kinetics Of

1. The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl.mg-1.h-1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. 2. Haemolymph Na+, Mg2+, K+, Cl-, SO42- and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% seawater and were found to be regulated within a narrow range. 3. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. 4. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. 5. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.

scholarly journals Kinetic Study of the Recovery of Phosphorus from Wastewater by Calcium Hydroxide Solution

2019 ◽  
Vol 25 (6) ◽  
pp. 19-29
Author(s):  
Shams Asem Mahdi ◽  
Raghad Fareed Qasim
Keyword(s):  
Oxalic Acid ◽  
Calcium Hydroxide ◽  
Phosphorus Concentration ◽  
Ambient Conditions ◽  
Residual Phosphorus ◽  
Mixing Speed ◽  
Dissolution Reaction ◽  
Best Value ◽  
Percentage Removal ◽  
Kinetics Of

This research presents a study for precipitating phosphorus (as phosphate ion) from simulated wastewater (5ppm initial concentration of phosphorus) using calcium hydroxide Ca(OH)2 solution. The removal of phosphorus by Ca (OH)2 solution is expected to be very effective since the chemical reaction is of acid-base type but Ca(OH)2 forms complex compound with phosphate ions called. Hydroxyapatite Ca5 (PO4)3OH. hydroxyapatite is slightly soluble in water. This research was directed towards sustainable elements as phosphorus. Kinetics of the dissolution reaction of hydroxyapatite was investigated to find the best factors to recover phosphorus. The effect of concentration of Ca(OH)2 (180- 380 ppm) on phosphorus precipitation on the outputs like the residual phosphorus concentration in the simulated solution, the percentage removal of phosphorus and the weight of the precipitate was also studied. The residual phosphorus decreased with increasing Ca(OH)2 concentration while the percentage removal, as well as the weight of the precipitate, increased with increasing Ca(OH)2 concentration at constant temperature and mixing speed. The best Ca(OH)2 concentration was obtained depending on the lowest amount of the residual phosphorus concentration. The best value obtained was 230 ppm at a fixed mixing speed of 400 rpm and a temperature of 20°C.  The best value for Ca(OH)2 concentration under fixed stirring speed and temperature was applied on a real wastewater taken from the detergent factory. The percentage removal was 30. 69% due to the complexity of the real sample. Oxalic acid was chosen to dissolve hydroxyapatite because it is an organic acid, less hazardous than mineral acids and of less cost. Kinetics of the dissolution reaction of hydroxyapatite in (160 ppm) concentration oxalic acid under ambient conditions (20°C and 1 atm (and mild stirring (200 rpm) was studied using the differential method for determining the order of the reaction which was 0.4296 and the rate constant 0.0743 (L/mg)-0.5704. min-1. The reaction was considered as a rate-controlled reaction.  

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