In this study, experiments have been conducted to evaluate the removal of nutrients from synthetic wastewater using a moving bed biofilm process. For this purpose, the process was applied in series with anaerobic, anoxic, and aerobic units in four separate reactors. Moving bed biofilm reactors were operated continuously at different loading rates of nitrogen and phosphorus and different hydraulic retention times. In addition, for kinetic analysis, first-order substrate removal, Grau, and Stover-Kincannon models were tested with the experimental data. Based on the results obtained, a close to complete nitrification with an average Total Kjeldahl Nitrogen (TKN) removal efficiency of 99.72% was obtained in the aerobic reactor under optimum conditions. In this reactor, the average specific nitrification rate was 1.92 g NOx-N/kg VSS.h. During the study, statistically significant correlation was observed between the aerobic phosphorus removal rate and the anaerobic phosphorus release rate. Under optimum conditions, the average total nitrogen and phosphorus removal efficiencies were 80.9% and 95.8%, respectively. Finally, based on the kinetic analysis and with regard to nitrogen and phosphorus removals, the Stover-Kincannon model was selected as suitable for analyzing the experimental data and modelling of the moving bed biofilm process.

In this research, an experimental study to evaluate nutrient removal from synthetic wastewater by a labscale moving bed biofilm process was investigated. Also, kinetic analysis of the process with regard to phosphorus and nitrogen removal was studied with different mathematical models. For nutrient removal, the moving bed biofilm process was applied in series with anaerobic, anoxic and aerobic units in four separate reactors that were operated continuously at different loading rates of phosphorus and nitrogen and different hydraulic retention times. Under optimum conditions, almost complete nitrification with an average ammonium removal efficiency of 99.72% occurred in the aerobic reactor. In the aerobic reactor, the average specific nitrification rate was 1.92 g NOx-N (NOx-N=NO2-N +NO3-N) produced/kg volatile suspended solids. Hour (VSS.h). Denitrification rate increased with increasing NOx-N loading in the second anoxic reactor. The aerobic phosphate removal rate showed good correlation with the anaerobic phosphate release rate. Under optimum conditions, the average total nitrogen and phosphorus removal efficiencies were 80.9% and 95.8%, respectively. As a result of the moving bed biofilm process (MBBR) kinetic analysis, the Stover- Kincannon model was chosen for modeling studies and experimental data analysis. The Stover-Kincannon model gave high correlation coefficients for phosphorus and nitrogen removal, which were 0.9862 and 0.986, respectively. Therefore, this model could be used in predicting the behavior or design of the moving bed biofilm process.

The efficiency of denitrification and enhanced biological phosphorus removal in biological nutrient removal activated sludge systems is strongly dependent on the availability of appropriate carbon sources. Due to high costs of commercial compounds (such as methanol, ethanol, acetic acid, etc.) and acclimation periods (usually) required, the effective use of internal substrates is preferred. The aim of this study was to determine the effects of slowly biodegradable compounds (particulate and colloidal), as internal carbon sources, on denitrification, phosphate release/uptake and oxygen utilization for a full-scale process mixed liquor from two large wastewater treatment plants located in northern Poland. Since it is difficult to distinguish the effect of slowly biodegradable substrate in a direct way, a novel procedure was developed and implemented. Four types of one- and two-phase laboratory batch experiments were carried out in two parallel reactors with the settled wastewater without pre-treatment (reactor 1) and pre-treated with coagulation–flocculation (reactor 2). The removal of colloidal and particulate fractions resulted in the reduced process rates (except for phosphate release). The average reductions ranged from 13% for the oxygen utilization rate during the second phase of a two-phase experiment (anaerobic/aerobic), up to 35% for the nitrate utilization rate (NUR) during the second phase of a conventional NUR measurement.

The application of microalgae in the treatment of wastewater has attracted considerable scholarly interest as a viable and environmentally sustainable alternative. In recent years, numerous combinations of microalgae and bacterial consortia have been investigated to evaluate their efficacy in the remediation of wastewater originating from various sources. The essential criteria for assessing their performance encompass their capacity to eliminate nutrients such as nitrogen and phosphorus, in addition to heavy metals including arsenic, lead, and copper. This study examines the efficiency of microalgae-based systems in treating wastewater, comparing them with traditional treatment methods. It also delves into the characteristics of wastewater, conventional treatment techniques, and the mechanisms used for nutrient and heavy metal removal. Microalgae have demonstrated remarkable potential, achieving removal rates of up to 99.6% for nitrogen, 100% for phosphorus, and 13–100% for heavy metals across various wastewater types. Despite these advantages, microalgae-based treatment systems face certain challenges. Their performance is influenced by factors such as temperature, biomass productivity, osmotic pressure, pH, and oxygen concentration.

To investigate the effects of nitrogen and Nitroxin bio-fertilizer application on yield, nutrient concentration, and total nutrient uptake in wheat shoots, a greenhouse experiment was carried out in a factorial completely randomized design with three replications. Treatments included two levels of Nitroxin (0 and 10 ml/kg of soil) and five nitrogen levels (0, 50, 100, 150, and 200 mg/kg of soil). Results showed that Nitroxin application significantly increased yield as well as the concentration and total nitrogen uptake, uptake of phosphorus, iron, and manganese in wheat shoots. Application of nitrogen increased yield, total uptake of nitrogen, potassium, iron, zinc, manganese, and copper as well as the concentration of nitrogen, potassium, zinc and manganese of wheat shoots, however, total uptake and concentration of phosphorus was reduced significantly. According to these results, combined use of nitrogen and Nitroxin is suitable for achieving the maximum yield of wheat shoots.

During the recent decades, the increasing trends in nitrate ion concentration in ground water sources have meant more research to find effective procedures for the prevention of even more water contamination by nitrogen sources. In this study a pilot was designed to examine the application of biological method for eliminating nitrate from the water of well No.903 of  ehrabad Airport, Tehran, Iran. Design, installation and running processes were done from April to November 2003. A fixed biological bed containing five-centimeter trunk pipes 16 mm in diameter were installed in the reactor and the system was operated with upflow current. Instead of Methanol, Acetic acid was used as the carbon source because of its easier acceptance by the public, lower price and availability as well as easier storage. The pilot was run in different hydraulic retention times from 48 h up to one hour. Considering economical, operational and maintenance factors, retention time of 2 h was determined to be optimum, in which 77% nitrate removal was achieved. Considering a ratio of 2 for COD/N, inlet COD of about 140 mg/L and the optimum retention time, COD removal of about 80% is also accomplished in this process. The amount of nitrite concentration, pH values, COD and turbidity is also evaluated versus different hydraulic retention times.  

Domestic wastewaters are one of the main sources of contamination and diseases. However, they can be treated and potentially reused if certain organic and inorganic compounds and molecules are eliminated. Novel environmentally friendly proposals are available, such as the use of bioremediation mediated by microalgae capable of efficiently upcycling different quantities of phosphates and nitrates. Thus, in the present study, we evaluated the consumption capacity of nitrates and phosphates present in samples of domestic wastewater by cultures of Chlorella sp. and Desmodesmus sp., two microalgae with nutrient removing abilities, to propose novel wastewater treatment alternatives. For this purpose, we assessed the microalgae growth in domestic wastewater, cultured using the batch system, under greenhouse conditions by reading the wavelength and obtaining the cell density using a multiparameter photometer and two equations for each type of microalgae. Then, the rate and mean percentage of nitrate and phosphate removal were obtained and compared using two previously reported equations applied in similar culture conditions. Both microalgae grew in wastewater samples mostly by day three to four, showing similar growth tendencies without alterations and having a progressive increase in cellular density. Nitrate concentrations in all experimental groups were reduced to up to 90% on the fourth day, the initial phosphate concentration of 30. 0 mg/L was reduced to 3. 5 ± 2. 1 mg/L with the Desmodesmus sp. treatment and to 9. 2 ± 1. 0 mg/L in the Chlorella sp. group. Desmodesmus sp. was the most efficient in the consumption of nitrates and phosphates, obtaining 96. 5 ± 8. 91 % and 88. 3 ± 4. 29 % of removal, respectively, while Chlorella sp. obtained 95. 0 ± 8. 0% and 69. 3 ± 2. 8%. Likewise, representative values of removal were obtained with the targets used in the laboratory tests.