The paper presents the results of studies concerning the designation of COD fraction in raw wastewater. The research was conducted in four municipal mechanical-biological sewage treatment plants and one industrial sewage treatment plant. The following fractions of COD were determined: non-biodegradable (inert) soluble SI, biodegradable soluble fraction SS, particulate slowly degradable XS and particulate non-biodegradable XI. The methodology for determining the COD fraction was based on the ATV-A131 guidelines and Łomotowski-Szpindor methodology. The real concentration of fractions in raw wastewater and the percentage of each fraction in total COD are different from data reported in the literature.
Increased production and consumption of drugs influences the pollution pharmaceuticals. Recent years have seen a significant increase in the consumption of non-prescription medicines, among which, are a large group of non-steroidal anti-inflammatory drugs (NSAIDs). Research conducted in Poland and abroad showed the presence of NSAIDs, both in treated wastewater in surface waters and drinking waters. One of the most frequently detected drugs in the environment is diclofenac, belongs to NSAID. Its concentration in surface waters range from 9 to 3363 ng/L. Traditional wastewater treatment plants are not specialized enough in removing the pharmaceuticals and their metabolites, and with purified wastewater are introduced into surface waters. Diclofenac concentrations in treated wastewater range from 0.29 to 2.5 μg/L, the average removal efficiency is about 40%.
The article is the literature review on the importance of trace elements supplementation in the methane fermentation process. The production of biogas, including methane, as well as the efficiency of the process depend on the substrates to be fermented. Substances supplied with the substrate as well as products generated in the decomposition phases can inhibit the process. The factor limiting fermentation is the rate of enzymatic hydrolysis of substrates. Certain compounds, such as alkanes, alkenes, biphenol, aromatic hydrocarbons, alcohols and ketones, are not directly susceptible to hydrolysis. They undergo this process in the presence of extracellular enzymes.
The instability of the methane fermentation process described in the literature may be related to the lack of trace elements or micronutrients. Trace elements (Co, Ni, Cu, Mn, Fe, Zn, Se and Mo) are components of enzymes, some bacterial nucleic acids and essential for the synthesis of vitamins. The role of some trace elements, eg. Fe or Mo, has been well understood, while the importance of others still needs to be clarified. Literature data indicate that supplementing trace elements not only prevents process inhibition, but can also improve its performance by providing higher methane production.
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