Artificial mixing to reduce growth of the blue-green alga Microcystis in Lake Nieuwe Meer, Amsterdam: an evaluation of 7 years of experience

2001 ◽  
Vol 1 (1) ◽  
pp. 17-23 ◽  
Author(s):  
E. Jungo ◽  
Petra M. Visser ◽  
Jasper Stroom ◽  
Luuc R. Mur
Keyword(s):  
Water Body ◽  
Bubble Plume ◽  
Annual Fluctuation ◽  
Algae Biomass ◽  
Mechanical Parts ◽  
Living Space ◽  
Artificial Mixing ◽  
Flexible Pipes ◽  
Nitrogen Concentrations ◽  
Extensive Growth

The problem of Lake Nieuwe Meer (area = 1.3 km2, max. depth 30 m, Ptot = 500 mg/m3) was extensive growth of Microcystis with disturbing scum forming. Since 1993 the lake has been artificially mixed in summer by a bubble plume installation. The result is quite successful since the mass of Microcystis is up to 20 times lower than in the years before mixing and no scum is present any more. The study in Lake Nieuwe Meer showed a shift from cyanobacterial dominance (mainly Microcystis) to flagellates, green-algae and diatoms when artificial mixing was applied. Total phosphorus and nitrogen concentrations did not change as a result of mixing and had apparently no effect on the shift in the phytoplankton composition. The chlorophyll-a concentration was much lower in the mixed lake as a result of dilution. The total algae biomass decreased. The transparency did not improve. The total heat energy of the lake is slightly higher than before mixing but still remains in the range of annual fluctuation. The temperature on the surface is approximately 2°C lower. In the whole water-body oxygen was always higher than 5 mg/l. Living space for fish is therefore wider. The installation in Lake Nieuwe Meer consists of flexible pipes near the sediment, built in a way to prevent sediment erosion and transport into the water. There are no constructions in the water-body. All mechanical parts are on land. The layout of the installation is shown in Fig. 1. Installed compressor energy is 85 kW. This is equivalent to an upper middle-class motor-car. The design was made specifically for this problem. It is based on the physical data of the algae and the plant. It would be beneficial to use this 7 year's experience for further applications e.g. elimination of toxic algae in drinking-water reservoirs.

Modelling multi-species algal bloom in a lake and inter-algal competitions

2009 ◽  
Vol 60 (10) ◽  
pp. 2599-2611 ◽  
Author(s):  
Monzur Alam Imteaz ◽  
Abdallah Shanableh ◽  
Takashi Asaeda
Keyword(s):  
Water Quality ◽  
Algal Bloom ◽  
Ecological Model ◽  
Algal Species ◽  
Dynamic Responses ◽  
Bubble Plume ◽  
Deep Lake ◽  
Blue Green Algae ◽  
Artificial Mixing ◽  
Using Data

A numerical model was developed to simulate water quality and algal species composition in a deep lake. As artificial destratification is widely used in the lakes, a destratification (bubble plume) model was incorporated with the ecological model to simulate the dynamic responses of different species under artificial mixing. The ecological model predicts concentrations of PO4-P, NH4-N, NO3-N, DO and pH throughout the water column, all of which have a significant influence on the growth of different algal species. The model has been calibrated using data from Uokiri Lake (Japan) for two different species (Diatom and Cyanobacteria) with and without artificial mixing. The calibrated model was used to simulate different conditions of artificial mixing within the lake over a period of five months. The simulation results show that artificial mixing favors non-motile heavier species, such as Diatom, while preventing the growth of Blue-green algae. It is also demonstrated that intermittent operation of the artificial mixing is better for water quality amelioration than continuous operation.

scholarly journals Characteristic Analysis of Water Quality Variation and Fish Impact Study of Fish-Lighting Complementary Photovoltaic Power Station

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4822
Author(s):  
Peidu Li ◽  
Xiaoqing Gao ◽  
Junxia Jiang ◽  
Liwei Yang ◽  
Yujie Li
Keyword(s):  
Light Intensity ◽  
Dissolved Oxygen ◽  
Water Body ◽  
Water Layer ◽  
Solar Photovoltaic ◽  
Characteristic Analysis ◽  
Power Station ◽  
Algae Biomass ◽  
Photovoltaic Panels ◽  
Photovoltaic Power

Fish-lighting complementary photovoltaic power station organically combines aquaculture and renewable energy. In this study we aimed to develop a solar photovoltaic that is not confined to land. We used a shade net to simulate photovoltaic panels, and studied the effects of different proportions of photovoltaic panels on water and fish. The results showed that the average light intensity of the unshaded area and the shaded area were 16,661.7 Lux and 2437.0 Lux. The average light intensity of the shaded area was 85.4% lower than that of the unshaded area. The effective range of the shaded area for the light intensity of the water layer was 0 cm~30 cm. The temperature and pH in the water body showed a linear decreasing trend with the increase of the photovoltaic deployment ratio, and the dissolved oxygen showed an inverted “U”-shaped change characteristic, but this effect was limited. When the photovoltaic deployment ratio was 25% to 75%, the dissolved oxygen in the water body increases by an average of 2.37% compared to the unshaded area. The appropriate proportion of photovoltaic deployment did not affect the dissolved oxygen content in the water body. When the photovoltaic deployment ratio reached 75%, the number of algae species and algae biomass was the largest, and the fish production was the highest at 8094.6 kg·acre−1, which is an increase of 166.2 kg·acre−1 compared to the average yield in unshaded areas. Therefore, photovoltaic layout will not affect the growth of fish, and the proportion of 75% is the best layout choice.

INTERACTIONS OF OESTRONE AND TESTOSTERONE ON MAMMARY GLANDS OF MALE RABBITS

1961 ◽  
Vol 36 (1) ◽  
pp. 141-156 ◽  
Author(s):  
B. Bengtsson ◽  
A. Norgren
Keyword(s):  
Mammary Gland ◽  
Testosterone Propionate ◽  
Mammary Glands ◽  
List Type ◽  
Stunted Growth ◽  
Abnormal Growth ◽  
Growth Reaction ◽  
Extensive Growth ◽  
Higher Doses

ABSTRACT The effect of testosterone and oestrone on the mammary glands of castrated male rabbits was studied. Testosterone propionate was used in daily doses from 0.5 to 80 mg. The doses of oestrone ranged from 0.05 to 25 μg per day. Mammary glands were examined after 14, 28 or 56 days of injections. 1) Testosterone in doses below 20 mg failed to affect the mammary glands. With 40 or 80 mg a distinct, though abnormal growth reaction was consistently obtained. 2) Oestrone in doses lower than 0.5 μg did not stimulate mammary growth. With 0.5 μg and higher doses extensive growth of the mammary glands occurred. Stunted growth and secretion were found in the mammary glands of rabbits injected with 12.5 or 25 μg oestrone. 3) Testosterone in doses of 1 or 5 to 10 mg depressed or abolished the response of the mammary glands to 0.5 μg oestrone. When testosterone, in doses ineffective when given alone, was added to at least 3.125 μg oestrone, the mammary glands developed alveoli. The abnormalities produced by the highest doses of oestrone studied were exaggerated by the addition of testosterone. 4) The observations indicate a complicated interplay between the actions of testosterone and oestrone on the mammary gland of the rabbit. The interactions between testosterone and oestrone are presumably different from those observed between progesterone and oestrone.

MANUFACTURING GASEOUS PRODUCTS BY PYROLYSIS MICROALGAE BIOMASS

2019 ◽  
pp. 23-34
Author(s):  
N. I. Chernova ◽  
S. V. Kiseleva ◽  
O. M. Larina ◽  
G. A. Sytchev
Keyword(s):  
Raw Materials ◽  
Renewable Energy Sources ◽  
High Energy ◽  
Initial Mass ◽  
Solid Residue ◽  
Algae Biomass ◽  
Gaseous Products ◽  
Microalgae Biomass ◽  
Pyrolysis Liquid ◽  
Pyrolysis Gases

Algae biomass is considered as an alternative raw material for the production of biofuels. The search for new types of raw materials, including high-energy types of microalgae, remains relevant, since the share of motor fuels in the structure of the global fuel and energy balance remains consistently high (about 35%), and the price of oil is characterized by high volatility. The authors have considered the advantages of microalgae as sources of raw materials for fuel production. Biochemical and thermochemical conversion are proposed as technologies for their processing. This paper presents the results of the study of the pyrolysis of the biomass of clonal culture of blue-green microalgae / cyanobacteriumArthrospira platensis rsemsu 1/02-Pfrom the collection of the Research Laboratory of Renewable Energy Sources of the Lomonosov Moscow State University. An experiment to study the process of pyrolysis of microalgae biomass was carried out at the experimental facility of the Institute of High Temperatures RAS in pure nitrogen grade 6.0 to create an oxygen-free environment with a linear heating rate of 10 ºС / min from room temperature to 1000 ºС. The whole process of pyrolysis proceeded in the field of endothermy. The specific amounts of solid residue, pyrolysis liquid and gaseous products were experimentally determined. As a result of the pyrolysis of microalgae biomass weighing 15 g, the following products were obtained: 1) coal has the mass of the solid residue is 2.68 g, or 17.7% of the initial mass of the microalgae (while 9.3% of the initial mass of the microalgae remained in the reactor); 2) pyrolysis liquid – weight 3.3 g, or 21.9% of the initial weight; 3) non-condensable pyrolysis gases – weight 1.15 l. The specific volumetric gas yield (the amount of gas released from 1 kg of the starting material) was 0.076 Nm3/ kg. The analysis of the composition and specific volume yield of non-condensable pyrolysis gases formed in the process of pyrolysis, depending on temperature. It is shown that with increasing temperature, the proportion of highcalorie components of the gas mixture (hydrogen, methane and carbon monoxide) increases. The calorific value of the mixture of these gases has been estimated.

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