A purpose of the research was to develop a method for the preparation of novel organo-mineral fertilizers with the use of brown coal and biochars as organic additives. Brown coal was blended simultaneously together with inorganic materials used for the process of urea superphosphate production in a laboratory scale using a pan granulator and in larger scale using a rapid mixer granulator. Biochars were used for the coating purposes of the urea superphosphate granules on a laboratory scale using a pan granulator. Moreover, the aim was to measure and evaluate the physico-chemical properties of organic materials and the obtained organo-mineral fertilizer products and to study the effects of these products on the selected yield components of spring wheat such as grain yield per plant, spike number per plant, and plant height, in pot trials. Results showed that brown coal and biochars can be used as raw materials for production of fertilizer products. Brown coal contained about 50% of total humic acids while biochar contained nearly 6% of total humic-like substances. Brown coal based compound fertilizer granules produced in the large scale were characterized by particle hardness from 15.80 to 23.3 N while those produced in the laboratory scale were classified as "soft" (particle hardness below 2.3 N). The application of brown coal based fertilizers and two studied biochar coated fertilizers had a positive impact on the grain yield per plant of spring wheat.

The purpose of this research was to determine and evaluate the chemical properties of drilling waste from five well sites in Central and Eastern Poland. It was found that spent drilling fluids can contain high values of nickel and mercury (270 and 8.77 mg kg respectively) and can exceed the maximum permissible limits recommended by the EC regulations for safety of soils (75 mg kg for nickel and 1.5 mg kg for mercury). The heavy metal concentrations in the studied drill cuttings did not exceed the maximum permissible limits recommended by the EC regulation. Drilling wastes contain macroelements (e.g., calcium, magnesium, and potassium) as well as trace elements (e.g., copper, iron, zinc, and manganese) that are essential for the plant growth. It was stated that water extracts of drilling fluids and drill cuttings, according to anions presence, had not any specific constituents of concern based on FAO irrigation guidelines, the USEPA WQC, and toxicity values. X-ray diffraction analysis was used to understand the structure and texture of waste drilling fluid solids and drill cuttings. Analysis of the mineralogical character of drilling fluid solids revealed that they contained calcite, quartz, muscovite, sylvite, barite, dolomite, and orthoclase. Drill cuttings contained calcite quartz, muscovite, barite, dolomite, and barium chloride.

Due to the growing world population, the challenge for the agriculture industry is to produce the right amount of food. This is not possible without the use of fertilizers. Unfortunately, apart from having a positive effect on the yield parameters, they can also adversely affect the natural environment. The use of fertilizers in excess or in a poorly digestible form causes the migration of fertilizer components beyond the reach of the plant root system. In this way, nutrients enter the groundwater, surface water and the atmosphere, contaminating them. The consequence of such actions is further climate warming and the deterioration of water status and air quality. Suspension fertilizers are an interesting proposition that meets the requirements of modern agriculture. They combine the advantages of liquid and solid fertilizers. The liquid form ensures better digestibility of the nutrients, especially in periods of drought, and the concentration of the ingredients is comparable to that of solid fertilizers. At the same time, production costs are lower, which is related to the simplification of the technological process and the possibility of using cheaper raw materials. A valuable advantage of fertilizer suspension is the possibility of using hydrated waste substances in their production.

Phosphorus raw materials are non-renewable, and their resources are shrinking faster and faster as a result of increased fertilizer production. This is due to the increasing population and the need to produce more food. Phosphorus, on the other hand, is one of the main nutrients of plants, without which it is impossible to conduct intensive agricultural production. There are no economically significant phosphate resources in Europe, so they must be imported. That is why it is so important to reduce losses and recover this element from waste streams, which was reflected in the new EU Regulation 2019/1009. A prospective option is to use waste phosphates from the production of polyether polyols. Previous studies show that they contain about 20% phosphorus. Due to their high water content, the most advantageous form of their application is the production of fertilizers in the form of a suspension. The aim of the study is to assess the possibility of using waste phosphates from the production of polyols as raw materials for the production of suspension fertilizers.

The limited resources of phosphorus raw materials, which are located outside of Europe, make it necessary to obtain phosphorus from the waste stream. This is reflected in the new EU Regulation 2019/1009, which concerns making fertilizing products available on the market. Its main goal is to harmonize the standards for fertilizers obtained from organic or secondary raw materials in the EU and to create new opportunities for their production and sale. The fertilizer sector uses almost 90% of the phosphorus raw material, for which there is no substitute, and the demand for fertilizers is constantly growing, stimulated by the growing number of people. A substitute for expensive imported raw materials can be waste sodium–potassium phosphate from the production of polyols. This study analyzes the composition and form of waste from PCC Rokita S. A. from Brzeg Dolny in Poland, in terms of the possibility of using it in the production of fertilizers according to the new EU regulations. Research shows that it contains nearly 19% phosphorus, as well as potassium and sodium. Low-level impurities and low organic matter content classify it as a raw material for the production of inorganic fertilizers. Due to the high water content, the most advantageous form of its use is the production of fertilizers in the form of a suspension. A certain difficulty in the production of this type of fertilizer may be the layers of crystals of different sizes precipitating in the waste.

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