Inorganic coagulants, synthetic organic polymers and alternative natural coagulants are used to treat raw water into drinking water and in wastewater treatment. In this experiment, model dairy water and kaolin water were treated with four alternative coagulants. Trigonella foenum-graecum proved to be the best coagulant among the selected alternative coagulants.

Sludge water, a product of drainage of primary and activated sludge from the municipal wastewater treatment process, is rich innutrients, particularly nitrogen and phosphorus. Nitrogen and phosphorus are inorganic biogenic substances suitable for plantnutrition. Sludge water can be treated via electrodialysis. This process leads to two products, one is a diluate stream (solutionless concentrated than the input, contains some nutrients) and the other is concentrate stream (solution in which nutrients areconcentrated against the input). There is abundant research in nitrogen and phosphorus recovery from the concentrate stream, forexample in the form of struvite used for fertilizing. However, little attention has been paid to the huge volumes of diluate stream.The diluate stream can be used in agriculture as water suitable for irrigation, where the bonus of this product is a partial fertilizingcapacity. This way, wastewater can be used for irrigation and fertilizing having subjected the wastewater to agrochemical analyses.An important condition for the use of sludge water or diluate stream for irrigation is the absence of heavy metals and toxic substances.Still, if the water contains heavy metals, they can be removed with a relatively high success, for example by precipitation.Using wastewaster as water for agricultural purposes for irrigation is one of the new options to find new secondary sources of water.This theme is highly topical as it is important to reduce the consumption of quality water resources. These must primarily serve fordrinking purposes, and therefore it is necessary to search for alternative water resources.

Wastewater contains resources, which can be recovered for secondary use if treated properly. Besides research in zero liquid discharge solutions, the aim of the study was a simultaneous recovery of products from a wastewater treatment plant’s dewatering liquor. To be specific, we investigated a simultaneous recovery of struvite and irrigation water using electrodialysis (ED) in laboratory experiments. Two products were obtained from ED—concentrate and diluate. The concentrate was precipitated to obtain struvite. On average, 11 g of wet precipitate (including 17.58% of dry solids) were obtained from 1 L of concentrate. Crystal phases were confirmed by powder X-ray diffraction (XRD), with showing 94–97% recovery of struvite, while the remaining 3–6% were identified as hazenite. The average yield of crystal struvite was 1.76 g. Both struvite and hazenite may further be used as a fertilizer. Next, we suggest using the second ED product, the diluate, as irrigation water if it meets the irrigation water requirements. Attention was paid to the concentrations of dissolved solids (DS) in diluate, which decreased by an average of 93% compared to the input values in the dewatering liquor. In line with the observed Czech or EU standards indicators, we can say that the diluate can be used in agriculture, namely as irrigation water (Category I—water suitable for irrigation).

Digestate from biogas plants, formed by dewatering anaerobically stabilized sludge, is characteristic of high concentrations of phosphates and ammonia nitrogen suitable for further use. Phosphorus is an element widely used to produce fertilizers, and because of its continually shortening natural supplies, recycling of phosphorus is gaining on significance. Both phosphorus and nitrogen are important elements and their presence affect the quality of water resources. Both elements can contribute to eutrophication. At the same time, both phosphorus and ammonia nitrogen, are important elements for agricultural production, and therefore greater demands are being made on the effort to connect sewage treatment processes and the process of recycling of these nutrients. A suitable product of phosphorus and ammonia nitrogen are phosphates in the form of a structurally-poorly soluble precipitate of magnesium ammonium phosphate (struvite). This form of slowly decomposing fertilizer is distinguished by its fertilizing abilities. Compared to direct use of digestate as a fertilizer, struvite is more stable and can gradually release ammonia nitrogen for a long time without unnecessary losses. In the reported experiments, the precipitation efficiency of the recycling of ammonia nitrogen and phosphorus from the digestate liqour (liquid discharge from digestate) was, at a stoichiometric ratio of Mg2+: NH4+: PO43− (3.2: 1: 0.8) and a stirring time of 15 minutes, 87 % for ammonia nitrogen ions.

Polychlorinated substances, polyaromatic hydrocarbons, heavy metals and pesticides are among the priority even at low concentrations. The problem, however, is that such low concentrations are impossible to measure using most available methods. This researchfocused on the determination of selected priority substances – heavy metals, namely lead and cadmium, in which the determination ofPb and Cd in wastewater by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was preceded by water sample pre-treatment.The paper deals with the influence of the pre-treatment on the resulting measured values. Two processes were selected as pre-treatmentprocesses. The first pre-treatment procedure was a simple filtration using a filter paper for moderate filtration. As the second procedure, we applied decomposition of the sample by nitric acid in the open system. The pre-treated wastewater samples were subsequentlyexamined using ICP-MS. Based on the obtained results, we can conclude that decomposition of the sample by nitric acid in the opensystem is a more suitable pre-treatment method for water samples