water pollution project - Gimnazija Vic Ljubljana, Slovenia
Microplastics in washing machine wastewater
Authors: Maja Vidmar, 3.A, Ursa Pirc, 3.B.
Mentor: Alenka Mozer
Co-mentor: Dr Andrej Kržan
Keywords: microplastic fibres, polyester, washing machine wastewater, marine environment
Overview:
Plastic microfibres, which end up in wastewater via laundry, are a serious environmental problem. Due to their large specific surface area, they can absorb various contaminants and enter the food chain. Only two scientific articles can be found in the professional literature, focusing on small plastic fibres excreted when washing synthetic clothes.
The aim of the research task was to quantify the amount of fibres excreted during rapid washing and drying of polyester blankets. To filter the washing machine wastewater, a special filter system (pore size 200 x 200 µm) was constructed. The blankets were washed 10 times in three series of experiments: with water alone, with added detergent, with added detergent and fabric softener. The waste water was filtered each time, the blanket was tumble dried and the separated fibres were collected. The dry fibres were then weighed. Fibre type was verified by infrared spectroscopy; fibre morphology, pore size of the filters of the filter system and dryer were determined using a stereo microscope or. scanning electron microscope.
We found that the use of detergent / fabric softener has no significant effect on fibre emissions. Fibre loss stabilises after the fifth wash; fibre loss is further reduced slightly during drying. Our simple filtration system retains most of the extracted fibres; the amount and size of fibres smaller than 50 µm found in wastewater after filtration are very small. According to a rough, very conservative estimate from our research, one million inhabitants of a geographical region with cold winters would discharge about 120 kg of synthetic fibres into wastewater in a year. With a research project, we have shown that it is possible to significantly reduce microfibre emissions to the environment with a relatively simple way of filtering washing machine wastewater.
Model of a sewage treatment plant with solar disinfector
Author: Erazem Stonič
Mentor: Sonja Artač
Keywords:
plant treatment plant, solar disinfectant, treatment of polluted water
Overview:
Water pollution and drinking water shortages are two pressing problems worldwide today. In different parts of the world, they face shortage of drinking water due to climate change, as well as human intervention in the environment. Elsewhere, there is plenty of water, but only water is polluted. The main objective of my thesis is to complement and present one of the ways to purify polluted water, a plant purification system with added solar disinfectant, which enables the purification of water into drinking water. The aim of my research project is to use natural water purification processes, taking into account the chemical and microbiological properties of polluted water. The practical part of the research task involves designing, manufacturing and testing a model of a WWTP in combination with a solar disinfectant. There are many different types of treatment plants. When determining the type and size of a treatment plant, the most important factors are the amount and type of polluted water. Most treatment plants purify water into sanitary water, but do not meet drinking water standards. Therefore, getting drinking water from a treatment plant was a big challenge for me. To this end, I found a solution called solar disinfectant. It is basically based on the SODIS system, but it is a much more technically advanced solution, which on the other hand still only uses solar energy. I added a solar disinfector to the model of an already working treatment plant, which I designed according to my own idea, so it is an innovation in the field of plant treatment plants. Technically, it is a simple solution that is suitable for implementation in practice, economically acceptable and efficient for producing drinking water according to the applicable standards. The fact that the treatment plant and solar disinfectant rely exclusively on solar energy confirms that this is green technology that meets the criteria of sustainable development and efficient water management.
Wastewater treatment with green algae cultures
Authors: Andraž Kladnik, 3.a, Manca Zupan, 3.a
Mentor: Sonja Artač
Co-mentor: Mag. Borut Lazar, Marjeta Resnik
Keywords:
green algae, Chlorella vulgaris, Scenedesmus quadricauda, Pseudokirchneriella subcapitata, municipal wastewater treatment
Overview:
In the research paper, we first focused on the definition, evolution, classification, physiology, metabolism and importance of algae for the environment and economy. As we considered three different algal cultures (Chlorella vulgaris, Scenedesmus quadricauda, Pseudokirchneriella subcapitata), we briefly presented them in the theoretical section. We went on to examine wastewater sources, the methodology of their sampling and treatment in treatment plants. We were particularly interested in municipal wastewater, as we obtained samples of wastewater from the Domžale-Kamnik central wastewater treatment plant for the presented study.
The experimental work, carried out at the company AlgEn doo and at Gimnazija Vič, started with microscopy of algae cultures, which we used in further research. The algae were then inoculated in sterilised media and multiplied. These were then added to the wastewater samples. We made three samples with individual cultures of green algae and one with a mixture of all three cultures. For comparison, we also used a positive control - tap water with a mixture of cultures and a negative control - wastewater only. We ran three parallel series, for later possible comparison, and tracked changes in pH, nitrate content, nitrites, phosphates, oxygen and absorbance. Samples were run for five weeks and three measurements were taken - first after two weeks and then at one-week intervals. The results were presented and compared in the form of tables and graphically. We found that the green alga Scenedesmus quadricauda was most effective in removing nitrates. We also found that algal growth is affected by the composition of wastewater or. its impurities, which can inhibit algal growth or otherwise react with different products in the metabolic processes of algae.