Katarzyna Pawęska

Operating household wastewater treatment plants in the light of binding quality standards for wastewater discharged to water bodies or to soil

Abstract The study presents the legal requirements concerning the quality of wastewater discharged to waterbodies and to soil after treatment in household wastewater treatment plants located in agglomerations or outside them. The procedure of stopping the operation of a household treatment plant that doesn’t meet the statutory wastewater treatment efficiency was presented. The decision ordering to stop the use of a household wastewater treatment plant has to be preceded by a decision ordering to take measures to limit its adverse impact on the environment. The clarification procedure has to determine the adverse impact on the environment in a doubtless manner and it has to be reflected in the documentation. The assessment of adverse impact should take into account the binding standards of use of the environment. Stopping the operation of a household wastewater treatment plant may result in issuing a decision ordering the user to connect to the sanitary sewage system.

Wastewater treatment in submerged aerated biofilter under condition of high ammonium concentration

Abstract Treatment of wastewater produced in Service Areas (SA) located on expressways and highways is a worldwide problem because of increasing amount of roads and specific composition of those kinds of sewage. Insufficient removal of pollutants from wastewater discharged into surface water may cause serious environmental problems. In the present study efficiency of treatment of wastewater with high ammonium concentration in biological membrane system used on SA was investigated. Concentrations of ammonia nitrogen in wastewater flowing into bioreactor in none of the tested objects did not fall below 99.0 mg of N-NH4·dm−3. Because of high ammonium content in sewage and high pH reaching value about 9, it is almost impossible to create favorable conditions for microorganisms that run purification processes resulting in low efficiency of phosphorus and nitrogen removal (reduction of biogenic compounds did not exceed 15%). Treatment of wastewater consisting mainly of urine with commonly used biological membrane technology has to be widely tested to perform suitable quality of discharged wastewater, to provide safety of surface water environment.

SEASONAL CHANGES IN THE REDUCTION OF BIOGENIC COMPOUNDS IN WASTEWATER TREATMENT PLANTS BASED ON HYDROPONIC TECHNOLOGY

The study presents the results of the treatment of domestic and industrial wastewater with respect to the reduction of nitrogen and phosphorus compounds. The analysis encompasses the results of physical and chemical tests of effluents from two facilities based on hydroponic technology: wastewater treatment plants with hydroponic lagoons using the BIOPAX technology – Paczkow, Poland and the Organica technology – Szarvas, Hungary. Monthly treatment effectiveness was determined basing on these analyses. The composition of wastewater flowing into the lagoon (after mechanical treatment) and wastewater discharged to the collector in 2009–2011 was subject to physical and chemical analysis in both facilities. The effluent quality was determined basing on the concentration of total phosphorus, total nitrogen and ammonium nitrogen. Mean annual results of the operation of both objects were high. For the wastewater treatment plant in Paczkow, operating in the BIOPAX technology, the effectiveness of treatment with respect to total nitrogen throughout the analysed period ranged from 76.9–84.4%. Total phosphorus was eliminated from wastewater with an effectiveness of 96.4–98.0%. Such high reduction level was caused by the application of additional precipitation process in the chambers of activated sludge reactor. The hydroponic plant in Szarvas (Organica technology) was characterised by a high effectiveness of reduction with respect to ammonium nitrogen: 92.0–93.0%, while the reduction of total phosphorus fell into the range 49.3–55.3%.

SEASONAL CHANGES IN PHOSPHORUS LOAD FLOWING OUT OF SMALL AGRICULTURAL CATCHMENTS

In this article distribution of monthly phosphorus loads flowing out of two agricultural catchments which are located in different physiographic conditions of Lower Silesia was analysed. Loads of phosphorus runoff from the catchment located in the piedmont part of Lower Silesia in each month rarely exceed 0.10 kg P ∙ ha-1. The size of annual load is determined by loads obtained in two months of early spring. Much lower loads obtained for lowland catchment, located near Wroclaw. Values calculated for each month rarely exceed the value of 0.01 kg P ∙ ha-1. Culmination of loads bringing away is a bit more extended in a time compared to the catchment located on Sudety Mts. Foreland. Much higher loads are observed during the period from January to April – this period has a major impact on the size of phosphorus load that flows out from this catchment during whole hydrological year. The obtained results clearly indicate that the threat of watercourses and water reservoirs supply in phosphorus compounds from agricultural land is periodic and it is particularly high during early spring. Phosphorus load flowing out from the analyzed catchments is very diverse. From facility located on Sudety Foothill in hydrological year, during research period, flowed away average 0.81 kg P ∙ ha-1. Significantly lower values were obtained for second facility and it was average 0.15 kg P ∙ ha-1 during a year. The size of load discharged during a year is largely determined by amount of phosphorus load flowing out during winter half of the year (from XI to IV). In case of foothill catchment in this period flowed out average 0.56 kg P ∙ ha-1, which presents 69% of annual load and in lowland catchment this percentage was even slightly higher and was 73%.

ACTIVATED SLUDGE TECHNOLOGY COMBINED WITH HYDROPONIC LAGOON AS A TECHNOLOGY SUITABLE FOR TREATMENT OF WASTEWATER DELIVERED BY SLURRY TANKS

The paper presents information related to the use of hydrophytic technology combined with traditional activated sludge solution for wastewater treatment in areas without central sewage system. The analyzed wastewater treatment plant (WWTP) was operated in activated sludge technology with a hybrid activated sludge reactor where biomass is kept in a settled and suspended form. Treatment system was completed with a hydroponic lagoon. Hydroponic lagoon has been used as tertiary treatment, in which the self-cleaning processes with the participation of the plant has come to an additional reduction of nutrients. The analyzed three-stage treatment plant is located in the municipality of Nowa Sól. Only domestic wastewater delivered by slurry tanks is treated there in the amount of 60 m3/d. During the observation, high average concentrations of total nitrogen (201.0 mgN/dm3) was observed and organic matter expressed by COD reaching 1341.5 mgO2/dm 3 and BOD5 on the level of 246.3 mgO2/dm 3 were noted. A characteristic feature of the object designed for wastewater treatment delivered by slurry tanks is high irregularity of wastewater supply and high instantaneous loads of pollutants (the system does not provide expansion tank). The biggest inequality factor of the flow to the reactor was observed in December 2014 (Nd=3.9). During the observations days with no inflow of sewage also occurred. The study shows the dynamics of changes in the amount of delivered domestic wastewater and sewage flowing out of the treatment plant including inequality factor. Information about the quality of wastewater was used to determine the reduction of concentrations of pollutants such as organic matter, suspended solids, nitrogen and phosphorus.

Assessment of Groundwater Quality in Areas Irrigated with Food Industry Wastewater: a Case of Wastewater Utilisation from Sugar and Yeast Factories

This work presents the outcomes from two independent studies evaluating the chemical quality of groundwater in agricultural areas irrigated with wastewater from sugar and yeast industries. The evaluation was determined using chemical parameters representing typical contaminants of sugar industry wastewater (SIWW) and yeast industry wastewater (YIWW), and characterising the content of organic matter (BOD5), nutrients (NH4-N, NO3-N, TN and TP) and salts (Cl, SO4, Na and K). The studies reveal that food industry wastewater constitutes a valuable water-nutrient-rich medium that can be reused in agricultural applications as an alternative water resource for irrigation and nutrients for fertilisation. Furthermore, the reuse facilitates the sustainable discharge of wastewater through a soil-aquifer zone to the natural environment. This does not affect chemical quality of groundwater, which was comparable in areas irrigated and non-irrigated with SIWW and YIWW. Although some parameters (NO3-N, NH4-N, SO4, Cl and Na) displayed higher concentrations in groundwater from the fields irrigated with wastewater, these contents were within recommended health-based guideline limits defined in either the groundwater quality standards or the drinking water quality norms. Only the contents of K revealed an exclusive groundwater impact from wastewater irrigation. This was confirmed in statistical tests employing the Ward’s hierarchical clustering method, which exposed excessive amounts of K introduced into groundwater through irrigation with both SIWW and YIWW. However, this parameter is not considered to pose any health risk to humans or the environment, and its content is not restricted by quality guideline values for either groundwater or drinking water.

CHANGES IN THE MICROBIAL COMPOSITION OF MUNICIPAL WASTEWATER TREATED IN BIOLOGICAL PROCESSES

Municipal wastewater is characterized by diverse microbial content, largely dependent on their sources as well as many other factors like condition and health of their producer, but also environmental factors. The number and share of individual bacterial population in wastewater is changing during the process of their treatment in wastewater treatment plants. The microbial content of treated wastewater is significantly affected by the type of technology used for wastewater treatment. The paper presents the results of the species composition of bacteria present in the wastewater at various stages of treatment for the two different technologies. Samples of wastewater from hydroponic wastewater treatment plant and from the plant whose technology is based on biofilters were analysed. A key mechanism for wastewater treatment in both cases is biological treatment, using microbial activity that decomposes pollutants in the wastewater, which significantly contributes to changes in the species composition of bacteria comparing to microbiological composition of sewage flowing into the treatment plant. Analyses of microbial composition showed that in the objects consisting of preliminary tank and biofilter, composition of bacteria species is changing, but many species isolated from raw sewage is also found in treated wastewater. In the plant with hydroponic lagoon after wastewater treatment throughout the process system, bacteria present in raw sewage or in wastewater after biological treatment were not identified in the outlet.

CHANGES OF THE PHYSICOCHEMICAL COMPOSITION IN THE WATER FROM WATER INTAKES ON RURAL AREAS OF KLUCZBORSKI COUNTY

Due to a lack of centralized water supply network on rural areas, the main source of water for household use are shallow dug wells. The quality of water taken in this way is not a subject of law regulations in Poland which are connected with quality of water taken for human consumption, which is the reason why this kind of water do not often meet the standards. Wells that are no longer exploited by taking water for living purposes because of households’ connection to the central water supply, are becoming a problem The paper presents the results of physicochemical composition of water samples taken from shallow dug wells located on the rural areas. The concentrations of mineral forms of nitrogen, i.e. nitrates, nitrites further the concentrations of ammonia nitrogen and phosphate were analysed. Additionally, changes of pH and conductivity were measured. In the case of nitrate and nitrite highest concentrations exceeding the standards contained in the Regulation of the Minister of Health were observed in wells 1 and 3. During the study period, seasonal variation of concentrations of ammonium nitrogen were observed as reflected in the increase of the parameter in winter months. Ammonium was also an indicator whose concentrations exceeded regulated norms at least once during the research period in each of the tested wells. Phosphates concentrations in the analyzed samples were at the level 0.12–0.17 mg PO4/dm 3.