Biomass production and water purification from fresh liquid manure – Use of vermiculture, macrophytes ponds and constructed wetlands to recover nutrients and recycle water for flushing in pig housing

Analysis of approaches to waste management of pig farms

This paper aims to analyze effective approaches to waste management in agro-industrial cluster. It considers the studies confirming the relevance and importance of the development of technologies for processing and recycling of waste from the agro-industrial cluster, and, in particular, waste from pig farms. The methods of system analysis, information synthesis, statistical data analysis were used to identify the existing problems. The period from 2000 to 2020 was considered. The most popular directions and production branches have been identified. Quantitative analysis of scientific works on recycling and disposal of waste of agro-industrial cluster was carried out. Based on the data obtained, graphs were built, comparisons were made, conclusions were drawn about the demand for the development of resource-saving technologies, and waste recycling. Based on the analysis of the existing approaches, the authors proposed a cluster form of organization and waste management.

Macrophyte biomass productivity for heavy metal adsorption

The search for low cost adsorbents that have metal-binding capacities has intensified in the last decades. Some natural aquatic macrophytes have been studied as adsorbents to remove heavy metals. Macrophytes ease to propagate converts them into plague for many ecosystems while they are also considered by some activities as a residue; therefore its resignification implies positive environmental effects. Whereas these macrophytes can be obtained from water bodies where they develop naturally, controlled production in greenhouses may be more appropriate for its use as filling in fixed-bed reactors that must operate continuously throughout the year. This work focused on obtaining the macrophytes growth parameters in order to calculate the most proper greenhouse containers dimensions and their required cultivation periods to be employed in a determined fixed-bed reactor with a certain effluent flow to filter. These parameters include: the biomass yield, the area required to obtain certain dry weight of a given biosorbent, and the relative growth and propagation rates. Selected macrophytes species were Azolla pinnata, Salvinia molesta, Limnobium leavigatum, Lemna minor and Pistia stratiotes. The characterization of each biomass and the study of their performance as biosorbents were conducted for the removal of Cu (II), Pb (II) and Cr (VI) ions from aqueous solutions, always procuring the WHO guidelines for drinking water. Azolla pinnata resulted in the species with the highest percentage of dry weight (6.56%), and the lowest values of relative growth and propagation rates. This species was as well the most efficient in removal of Cu and Pb (96.7% and 99.4%, respectively), while Pistia stratiotes was better adsorbent for Cr with a removal of 58.8%. The possibility of metal recovery and macrophyte biomasses reuse was also proven. Given their natural abundance, elemental growth conditions and propagation rates, macrophytes represent a low cost alternative to the most efficient commercial adsorbents.

The use of microbial-earthworm ecofilters for wastewater treatment with special attention to influencing factors in performance: A review

With the unique advantages of lower operational and maintenance cost, the use of microbial-earthworm ecofilters (MEEs) for the wastewater treatment has been increasing rapidly in the recent years. This paper provided an overview of the research activities on the use of MEEs for removing pollutants from various wastewater throughout the world. However, the long-term effective treatment performance and sustainable operation of this system still remain a challenge since the treatment performance would be affected by design parameters, operational conditions, and environmental factors. In order to promote the treatment performance, therefore, this paper also provided and summarized the influencing factors of pollutants removal in MEEs. The design parameters and operational conditions of MEEs include earthworm species and load, filter media type, hydraulic loading rate, nutrient load, packing bed height, chemical factors and temperature. Lastly, this review highlighted the further research on these issues to improve performance and sustainability of MEEs.