Immobilization of Laccase in Alginate Beads

The elimination or degradation of micropollutants from wastewater is becoming ever more important nowadays. Using oxidoreductase enzymes to treat different micropollutants seems a promising solution. However, the viability of the process is highly dependent on the availability and stability of the applied enzymes. In order to improve the stability and provide faster reaction rates, enzymes can be immobilized in various carriers. Properties such as simple production, easy retention and biodegradable carrier material are advantageous, e.g. entrapping laccase in alginate beads. This paper shows the results of the preparation and characterization of immobilized laccase entrapped in calcium alginate beads. The technique of adding a mixture of sodium alginate and laccase dropwise into calcium chloride has been applied, improved and standardized to produce laccase-containing beads of uniform size and activity. For the purpose of characterization, a widely used substrate, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, was used to evaluate the performance of the laccase-containing alginate beads. In addition to the characterization of the laccase-containing alginate beads, the enzyme kinetic constants (= 26.43 µM, ax = 0.23 µM/min) were determined. The reduction in the activity during storage has been described by a decay constant (0.26 d−1 ) that provides information concerning the design constraints of the process. Results will be used to test the method in terms of the removal of organic micropollutants in continuous systems

Groundwater Remediation Using Biological and Photocatalytic Methods

The degradability of two commercially available pesticides was studied using heterogeneous photocatalytic and activated sludge treatment methods. The first pesticide contained 5% quizalofop-P-ethyl as an active ingredient and petroleum naphtha as a solvent, the latter causing difficulties both in photocatalytic and biological treatment methods. The active ingredient of the second compound was acetamiprid. The photocatalysis proved to be effective both under laboratory conditions (using UV light) and when exposed to sunlight, but the pesticides remained stable during the employed biological treatment. Preliminary information on its behaviour in soil was obtained from transport modelling

Enhanced Pollution Removal with Heat Reclamation in a Small Hungarian Wastewater Treatment Plant

The aim of the research is to outline the possibilities of utilizing waste heat in small municipal wastewater treatment plants. The facility, which was chosen as case-study, accepts about 2,300 m3 of raw sewage daily. In wintertime the wastewater temperature decreases to 10-14 °C which results in lower nitrification capacity based on measurement and validated model results. The excess heat of the wastewater would serve to increase the temperature of the aeration tank in order to enhance the microbiological activity and thus the efficiency of pollutant removal. The amount of reusable waste heat is calculated and with the help of dynamic simulation the effluent quality was determined to compare it with the original results. Increasing the temperature by 6 °C in the aerated tank, ammonium removal could be improved by 61%. This way not only the heat, but the nutrient pollution could be mitigated, too

Survey of Sars-Cov-2 Genetic Material Reduction During a Traditional Wastewater Treatment Technology

The transmission of Severe Acute Respiratory Syndrome Coronavirus-2 in a community can be monitored by a wastewater-based epidemiological approach due to fecal shedding. Although sewage surveillance has gained a considerable amount of attention over the last 16 months, an indirect issue within the topic is whether traditional wastewater treatment technologies are sufficiently efficient to eliminate the genetic material of SARS-CoV-2. Samples were taken from the Wastewater Treatment Plant in Nagykanizsa before the virus was concentrated, nucleic acid extracted and SARS-CoV-2 detected by RT-qPCR (Quantitative reverse transcription PCR). The influent and primary treated samples tested positive, while after the secondary treatment, all the results were negative. Consequently, the activated sludge process proved to be efficient in terms of the removal of SARS-CoV-2

Impact of water as raw material on material circularity - A case study from the Hungarian food sector

Measuring circularity is necessary to prove the feasibility of transforming linear technologies into circular ones. However, most of the circular economic researches consider water only as a medium. Food industry processes are excellent examples of systems that are hard to break free from linearity, albeit not impossible. This paper explores solutions to include water in circularity calculations using a Hungarian poultry processing plant as a case study. Two circular economic indicators, the questionnaire-type Circular Economy Indicator Prototype (CEIP) and the product-centric Material Circularity Indicator (MCI and MCI’) and the Water Footprint were examined in detail and modified to fit the needs of assessing circularity with water included as raw material. The calculations were supported by Life Cycle Assessment (LCA). The impact on circularity and the environment were quantified by considering different reuse scenarios. As the results of CEIP show, including water reuse in the technology or recycling for irrigation could increase the indicator values from low to medium-high level of circularity. However, the level of improvement highly depends on the amount of water used. LCA highlighted the significant environmental effects of packaging (<2% of product mass) and the relative benefits of recycling and reuse. The MCI’ values (including water as raw material) increased from 0.171 to 0.848 when water demand was reduced by 50% and 100% reused within the processes. This led to a reduction of 76% in the environmental effect. On the other hand, Water Footprint analysis showed that 99% of the water is incorporated in the product itself; therefore, technological water consumption should be treated separately from broiler breeding. The results show that a fairly linear process can be directed towards circularity. However, environmental benefits are not guaranteed with higher circularity points, and recycling may lead to unexpected results

Simulation of a Secondary Settler Based on Sedimentation Curves

The settlers of wastewater treatment plants are of the same importance as the activated sludge tanks. This role manifests in the course of simulating wastewater treatment systems as well. Several models describing the process of sedimentation were developed of which the one-dimensional models dividing the settlers into given layers are wide-spread. In this paper the parameter dependence of the Takács-model was studied. Samples were taken from the wastewater arriving to the secondary settler at different times in order to determine the settling profiles belonging to different concentrations. The Vesilind function and the maximum practical settling velocity were derived base on these data. Using three sets of measurement data the Takács model was fitted by modifying certain parameters. The simulation results gave an overestimation on the concentrations of the effluent in all three cases and there were differences of a few percents in the lowest layer as well. Taking the changes in the order of magnitude of the suspended solids concentration into consideration in the process of sedimentation i.e. it had to be decreased from 4000–6000 g/m3 to 8–12 g/m3 the higher values in the effluent layer are acceptable until they are below the permissible limit

Design and Optimization of Laccase Immobilization in Cellulose Acetate Microfiltration Membrane for Micropollutant Remediation

The industrial and environmental applications of laccase, especially in wastewater treatment, have gained focus in recent years. Therefore, developing the proper laccase immobilization techniques, which could improve the stability of the enzymes and simplify the required downstream processes, is needed. A novel two-step immobilization process was developed, resulting in cross-linked enzyme aggregates (CLEA) in the pores of the membrane. Laccase adsorption on a biodegradable cellulose acetate microfiltration membrane along with cross-linking was investigated to maximize the enzyme load and immobilization efficiency. The optimization was done regarding the: pH, temperature, enzyme concentration, adsorption time, cross-linker concentration, and temperature. It was concluded that the highest immobilization efficiency (76%) could be achieved in acidic buffers at 29 °C with high surface activity (1174 U·m−2) at the cost of partial denaturation and membrane fouling. The membrane was successfully utilized for the enzymatic treatment of diclofenac, and 58% removal efficiency was achieved. The results indicated that cellulose acetate is a suitable carrier for adsorption-based immobilization of laccase for the potential for environmental utilisation

Adapting the SDEWES Index to Two Hungarian Cities

Numerous cities aim to mitigate their contribution to climate change and provide a liveable environment in the context of sustainable development. In order to measure these efforts, benchmarking performance would be a good solution. Methods for environmental analysis have their limitations when it comes to evaluating a city and other aggregated indicators focus on certain aspects of a sustainable or liveable settlement. The SDEWES Index was used for benchmarking several cities of different sizes in terms of metrics related to energy, water and environmental systems successfully thus it was chosen to compare the performance of Veszprém and Zalaegerszeg, two environmentally conscious Hungarian county seats of roughly the same size and population. The SDEWES Index consists of 7 dimensions, namely energy consumption, industrial profile with CO2 emissions, CO2-saving measures, R&D, renewable energy potential and utilization, water and environmental quality, and social environment and sustainability policy. Each dimension is composed of 5 indicators that provide information on sustainable development of energy, water and environmental systems in cities. Using the SDEWES Index the strengths and weaknesses of the two cities are highlighted, locating those key parameters where improvement can be achieved. Both for Veszprém and Zalaegerszeg progress could be realized concerning energy-saving measures and the proportion of green areas could be increased. To improve the method and facilitate a more comprehensive comparison of cities of differing sizes, data should be provided concerning the territory or population. Also, the definition and inclusion of a worst and best case scenario that takes into account the parameters would be advantageous in terms of a comparison. These were named ‘horror’ and SDEWES cities by the authors, respectively

Red Mud as Adsorbent to Recover Phosphorous from Wastewater Streams

Background: Phosphorous (P) is an essential nutrient with finite and non-renewable resources; however, it can cause eutrophication in freshwater. The use or storage of red mud (RM), a by-product of alumina production with high iron and aluminium content, poses another environmental issue. Objective: This paper examines the possibility of P recovery from various wastewaters and landfill leachate with RM. Methods: Pulverized, on-site pre-treated red mud was used. Synthetic P solution, poultry wastewater effluent, the spiked effluent of a municipal wastewater treatment plant and landfill leachate were examined. Results and conclusions: Removal efficiencies of 0.41–1.24 mg P/mg RM for the wastewater effluents and 0.10–0.13 mg P/g RM for the leachate resulted in a decreased phosphorous concentration (0.02–0.57 mg P/L) for each liquid. Despite the doses being substantially higher than the stoichiometric value (103 mg P/g RM), the dosage increase did not result in a considerable cost increase. Further investigation is in progress to insert this solution into existing wastewater treatment technologies to facilitate excellent effluent quality and utilize the nutrient content of red mud