M3 Of Wastewater Research Articles

Advanced manufacture of polyphenols, essential oils and bacterial cellulose in a novel citrus processing wastewater biorefinery.

Herein, a citrus processing wastewater-based biorefinery has been developed manufacturing essential oils, polyphenols and bacterial cellulose. Liquid-liquid extraction was evaluated for isolation of essential oils assessing different organic solvents, recovering 0.45kg of essential oils per m3 of wastewater using n-heptane. Amberilte® XAD4, XAD16N and XAD7HP, PurSorb™ PAD900, biochar and activated biochar were compared as adsorbents for polyphenols recovery, demonstrating that the adsorption isotherms of the resins applied could be closely predicted using the Langmuir model. Adsorption and desorption density experiments exhibited that the phenolic content present in citrus processing wastewater could be efficiently recovered using PAD900, yielding 0.78kg of polyphenols per m3 of wastewater. The sugar content remaining following polyphenols adsorption was applied for bacterial cellulose production employing Komagataeibacter sucrofermentans DSM 15973 determining the biopolymer's production efficiency as well as morphological and structural properties at different carbon to free amino nitrogen ratios. The higher content of the biomaterial was obtained employing 15.0 carbon to free amino nitrogen ratio, which yielded 4.4kg of biopolymer per m3 of wastewater. The study has shown that by decreasing the carbon to free amino nitrogen ratio could enable enhancing the water-holding capacity of bacterial cellulose, exhibiting that the control of fermentation conditions could potentially enable tailoring the properties of the biomaterial for certain industrial applications. The bioactive, antioxidant and preservative properties of essential oils and polyphenols constitute the aforementioned products significant for a range of industrial applications within the pharmaceutical, cosmetics and food sectors.

Comprehensive Analysis and Emission Reduction Pathway of GHG Emissions at a Wastewater Treatment Plant in Suzhou

Taking a sewage treatment plant in Suzhou City, Jiangsu Province, as an example, the greenhouse gas （GHG） emissions generated in the sewage treatment system were calculated using the carbon balance method and the emission factor method. The environmental impacts and economic aspects of different treatment units in wastewater treatment plants were analyzed using life cycle assessment, cost-benefit analysis, and data envelopment analysis models, and emission reduction pathways were proposed. The results indicated that the total GHG emissions （in terms of CO2） from a certain municipal wastewater treatment plant in Suzhou were 6 653.08 kg·（104 m3）-1, with direct and indirect GHG emissions accounting for 29.22% and 74%, respectively. The reuse of treated effluent achieved a reduction of 3.3% in emissions. The biological treatment phase and the sludge treatment phase were the main impact stages for GHG emissions at a certain wastewater treatment plant in Suzhou, where the high-power equipment, specifically the blowers used in the biological treatment phase, and the use of polymeric ferric sulfate agents in the sludge treatment phase were the primary factors contributing to GHG emissions. Life cycle assessment analysis revealed that electricity consumption, direct CO2 emissions, pollutant concentration in the effluent, and the use of chemical agents at wastewater treatment plants had negative impacts on global warming, atmospheric acidification, and eutrophication of water bodies. Calculations indicated that for every 10 000 m3 of wastewater treated, the sewage treatment plant achieved a net benefit of 13 630 RMB. However, from April to May 2023, the scale efficiency of the sewage treatment plant was less than 1. This indicates that during this period, the proportion of output increase was less than that of input increase, demonstrating an irrational structure of input-output. After June, through enhancing the overall operational load, advancing technical improvements, and management efforts, the optimization of scale efficiency was achieved. A sewage treatment plant in Suzhou could achieve the goal of being "green and low-carbon" by installing high-efficiency pumps and fans, utilizing solar photovoltaic and water source heat pump systems, and making process improvements.

Deciding on the priority of process parameters using the analytical hierarchy process in electrochemical wastewater treatment and investigation of paint wastewater treatability

In planning electrochemical treatment processes, it is thought that decision-making tools should be used in the selection of the main parameters that are likely to affect pollutant removal. According to detailed research in the literature, no previous study has systematically prioritized process parameters in electrochemical wastewater treatment using the analytical hierarchy process (AHP). In this study, published articles in the literature on the subject were used to determine which parameters were used in the treatment processes and with what frequency. Using the obtained results, the priorities of the process parameters were estimated with the help of AHP within the scope of the removal efficiencies and treatment cost criteria. According to the AHP analysis results, it was determined that the most effective parameters for both electrocoagulation and electrooxidation processes were pH (0.241), current density (0.171), voltage (0.171), conductivity (0.107), concentration (0.105) and reaction time (0.094). Four of the independent parameters were selected and treatability studies were carried out using both electrocoagulation (with Al electrode pair and Fe electrode pair) and electro oxidation (with Graphite electrode pair and Ti electrode pair) methods for different levels of each parameter. The pH, current density, voltage, and reaction time were chosen as independent parameters based on decision making process. Unit costs for removal of chemical oxygen demand with Al, Fe, graphite, and Ti electrodes were obtained as 1.05, 2.56, 0.074, and 14 USD per m3 wastewater, respectively. Unit costs for removal of color with Al, Fe, graphite, and Ti electrodes were obtained as 0.68, 1.20, 0.074, and 14 USD per m3 of wastewater, respectively. In addition, nine batch kinetic studies were conducted for optimum conditions obtained from pre-treatment studies with Al and Fe electrodes. Removal of chemical oxygen demand was achieved at 64 % with aluminum and iron electrodes at 40 and 70 min, respectively. The results obtained from kinetic studies showed that adsorption of organic substances fit the 2nd-order kinetic model and the correlation coefficient was 0.95 and 0.96 for aluminum and iron electrodes, respectively.

Does stricter sewage treatment targets policy exacerbate the contradiction between effluent water quality improvement and carbon emissions mitigation? An evidence from China

Rapid expansion and upgrading of wastewater treatment facilities globally, driven by stricter wastewater policies, significantly contribute to carbon emissions. China has contributed 30 % of carbon emissions in the world, 1 % of which comes from wastewater treatment, necessitating more understanding of the impact of policies, especially the stringent “10-Point Water Plan” policy. From a micro perspective, this study uses the difference-in-differences method to analyze the impact of wastewater treatment policies on water and carbon issues in China’s 2894 wastewater treatment plants (WWTPs), and delves into the heterogeneity, and mechanisms across various dimensions. The results show that stricter sewage treatment policy decrease effluent concentration of the chemical oxygen demand (COD) by 2.35 %, and also cause a 1.74 % rise in carbon emissions per 10,000 m3 of wastewater treated, intensifying the short-term contradiction, while the contradictions may fall in the long term. It is more significant in southern regions and the cities with lower environmental regulation intensity. Also, there are significant differences in different wastewater treatment technology and scale. Significant improvements in effluent water quality are observed in WWTPs with 100,000 to 200,000 m3/day capacity and those using biofilm treatment technology. Through mechanism analysis, reasonable expansion of urban pipelines and WWTPs, promotion of biofilm treatment technology, reduction of energy consumption, and improvement of pollutant reduction efficiency are feasible paths to improve water quality and reduce carbon emissions. This research provides a perspective on solving water-carbon contradictions in WWTPs, holding critical significance for urban wastewater treatment and carbon emission management.

A study of continuous-flow electrocoagulation process to minimize chemicals dosing in the full-scale treatment of plastic plating industry wastewater

A continuous-flow electrocoagulation unit was used to replace the existing chemical coagulation in plastic plating industry wastewater treatment plants, aiming to enhance pollutant removal and cost efficiency. This study was conducted at an on-site wastewater treatment plant, with the electrocoagulation process monitored for nine consecutive months. A novel electrocoagulation unit equipped with multi-rod helical systems (i.e., made of an iron anode and a stainless-steel cathode) was used in this study, with the treatment flow adjusted to optimize the operational costs. The results indicate that energy consumption can be maintained at 7200 kWh/month while achieving >99 % removal of heavy metals (Cr, Ni, and Cu), with removal rates of 78.64 ± 0.13 mg/L.day (Cr), 105.47 ± 0.07 mg/L.day (Ni), and 38.30 ± 0.09 mg/L.day (Cu). The chemical cost was reduced by approximately 50 %. Furthermore, an over 50 % reduction in sludge production was achieved, with the acid and alkaline by-products entirely recycled. Compared to the previously applied chemical coagulation, electrocoagulation can reduce operational costs from US$ 6.11 to US$ 2.87 per m3 of wastewater treated. These results confirm that electrocoagulation can be optimized and implemented to replace conventional chemical coagulation.

Assessment of Energy Self-Sufficiency of Wastewater Treatment Plants—A Case Study from Poland

Currently, one of the main goals is to make municipal wastewater treatment plants (WWTPs) energy-neutral. However, advanced wastewater treatments and sewage sludge processing are still classified as highly energy-intensive. In this study, the energy self-sufficiency potential assessment of the WWTP located in Krosno (Poland) was evaluated. Moreover, the possible paths for improving the energy balance of the analyzed facility are presented in this paper. The performed evaluation indicated that in 2016–2019, the energy consumption at WWTP Krosno varied from 0.25 to 0.71 kWh/m3 of wastewater (average 0.51 kWh/m3), and the highest energy utilization values in each year were recorded around the summer season. An analysis of the data showed that as the pollutant load flowing into the WWTP increased, its energy utilization decreased. Such results indicate that the treatment cost per cubic meter decreases as the load increases due to the capital cost being the same. The estimated self-sufficiency of the facility in the years analyzed was 50.5%. The average energy recovery from 1 m3 of wastewater was 0.27 kWh/m3, and the average energy recovery from 1 m3 of biogas was 1.54 kWh/m3. Since the energy balance of this wastewater treatment plant, determined primarily by the continuously increasing cost of energy purchases, has to be improved, two courses of action were identified that will allow for increasing self-sufficiency. The co-digestion strategy was indicated as the easiest solution to implement, given the on-going anaerobic stabilization of sewage sludge at this WWTP. Moreover, the possible co-substrates that can be obtained from local suppliers were indicated. The second course of action, which requires a thorough economic analysis, is sludge pre-treatment, which might improve sewage sludge properties, resulting in a more favorable biogas yield.

Sustainable utilization of pineapple fruit waste as a potential source of regenerated cellulose for the development of high-strength paper

Regenerated cellulose (RC) was prepared from pineapple crown waste fiber (PCWF) with a yield of about 45 %. The RC was blended with hardwood pulp (HP) to improve the mechanical properties of the paper. The composite paper with improved tensile index from 16.87 ± 0.75 NN mm/g to 28.98 ± 1.2 NN mm/g and burst index from 0.974 ±0 .083 kkPaPa mm22/g to 1.827 ±0 .153 kkPaPa mm22/g was developed by blending 20 % RC with 80 % HP. It was calculated that the production of one tonne of RC generates about 130 m3 of wastewater and it can be recycled after treatment with electrocoagulation technique. After wastewater treatment, chemical oxygen demand (COD) was reduced 84.8 %, total suspended solid (TSS) by 95.6 %, total dissolved solids (TDS) by 30.4 %, and biochemical oxygen demand (BOD) by 95.8 %. Importantly, the recycling behavior by reusing/recycling the treated wastewater for the regeneration process was investigated and a yield of about 42 % of the RC was observed.

Trickling filter systems for sustainable water supply: An evaluation of eco-environmental burdens and greenhouse gas emissions

Despite the global water crisis, the significant potential of trickling filter systems as a crucial auxiliary option for sustainable water supply has received insufficient attention. Therefore, this study presents the first-ever evaluation of the environmental impacts of trickling filter application in wastewater treatment, focusing on eco-environmental burdens. Additionally, the study explores greenhouse gas emissions, energy, and exergy footprints, providing novel insights into the environmental implications of using trickling filters for wastewater treatment. The study's findings indicate that the consumption of heat and electricity in trickling filters has significant environmental impacts, particularly on land use (93.24%), freshwater/marine eutrophication (∼81.98%), and human health (45.36%). The majority of the energy required for trickling filter operation is supplied by fossil fuels (96.02%), resulting in increased greenhouse gas emissions (65.58%). The exergy of trickling filters is highly efficient, accounting for over 95% of the system's energy. Mathematical modeling reveals that anaerobic digestion and secondary clarifier have the highest energy consumption, with contributions of 94.65% and 2.63%, respectively. Construction expenses account for almost 88% of the total cost, with anaerobic digestion (42.15%) and trickling filters (35.39%) being the most costly components. The cost of treating 1 m3 of wastewater is estimated at 0.52 $/m3. Sensitivity analysis demonstrates that electricity (14.66%) and heat (18.65%) significantly impact terrestrial ecotoxicity and land use, respectively. This study presents a framework for future investigations in this field.

Direct generation of Zn metal using laser-induced ZnS to eradicate carbon emissions from electrolysis Zn production

In response to the goal of net-zero emissions proposed by Intergovernmental Panel on Climate Change, Chinese government has pledged that carbon emissions will peak by 2030, and achieve carbon neutrality by 2060. However, the high carbon energy structure of traditional industries has aggravated environmental problems, such as greenhouse effect and air pollution. The goal of carbon neutrality will be difficult to achieve without the development of disruptive theories and technologies. The electrolytic zinc industry requires high-temperature roasting at ∼1000 °C, generating large amounts of greenhouse gases and SO2. High concentrations of sulfuric acid (200 g/L) are subsequently used for electrolysis, and each ton of zinc produced generates 50 kg of anode slime with lead content of up to 16%, as well as 0.35 m3 of wastewater containing zinc and lead. To solve these problems, an optical metallurgy method is proposed in this study. The proposed method uses laser-induced photoreduction to decompose ZnS and reduce metal ions to metal. Results indicate that Zn0 and S8 can be detected on the surface of ZnS at a specific wavelength and laser fluence. The generation mechanism of Zn0 is such that laser induces an electronic transition that breaks ionic bond in ZnS, resulting in its decomposition and photoreduction to Zn0 under an inert argon gas atmosphere. This method does not reduce other metals in the mineral since it does not use high-temperature roasting, providing a new way of producing high-purity metal without greenhouse gas emissions and heavy metal pollution caused by traditional zinc electrolysis.

WATER USE AS A FACTOR IN THE FORMATION OF ECOLOGICAL SAFETY OF THE NICHLAVA RIVER BASIN

The purpose of the article is to determine the level of pollution of the Nichlava River and the structure of water use in its basin from the point of view of forming the ecological security of the region. The following methods were used in the course of the study: evaluation, geoecological analysis, statistical, geoinformation, geochemical and cartographic. Ensuring the ecological safety of a small river basin directly depends on the hydroecological parameters of the river itself. Therefore, studying the pollution of the Nichlava River and the quality of its waters is an important and urgent scientific-practical task.
 Based on the analysis of statistical data from the State Agency of Water Resources of Ukraine, we found that in 2021, 450 thousand m3 of water was withdrawn from natural water bodies in the Nichlava River basin, including 280 thousand m3 from underground water intakes. The used 600 thousand m3 of fresh water, including 260 thousand m3 for drinking and sanitary needs and 340 thousand m3 for production needs. The total water discharge in the Nichlava River basin in 2021 amounted to 660 thousand m3 of water. A total of 650 thousand m3 of wastewater was discharged into the basin's surface water bodies over the year. Including 80 thousand m3 of polluted wastewater and 180 thousand m3 of normatively clean wastewater without wastewater treatment. In 2021, 390 thousand m3 of wastewater was treated at the wastewater treatment plants in the study area. In 2016-2021, 668 thousand m3 of contaminated or insufficiently treated wastewater was discharged into the Nichlava River. Together with the polluted wastewater, 1147 tons of pollutants entered the river. The calculated polluting wastewater discharge coefficient for the Nichlava River basin is 0,12, which indicates not a high concentration of pollutants in the wastewater. However, despite the significant amounts of pollutants discharged into the surface water bodies of the Nichlava River basin, all indicators of the chemical-biological composition of water in the control section of the river meet ecological standards. Therefore, the level of ecological safety in the Nichlava River basin can be considered satisfactory. Promising measures to improve the ecological condition of the river and its basin include optimizing the structure of land use, restoring and preserving coastal protection strips, reconstructing inoperable sewage treatment plants in settlements, and eliminating unauthorized discharges into surface water bodies.
 Therefore, the introduction of effective mechanisms of rational water use in the Nichlava River basin should be a priority area of environmental policy at the regional level of new administrative districts and the local level of territorial communities. The river basin management plan, which must be developed, should include measures to restore the centralized drainage system in small and large settlements, reconstruction of treatment facilities and elimination of unauthorized discharges into surface water bodies.
 Key words: Nichlava River, polluted runoff, water use, water quality.

Fabric dyeing wastewater treatment and salt recovery using a pilot scale system consisted of graphite electrodes based on electrooxidation and nanofiltration

In this study, color removal, suspended solids removal, and salt recovery were investigated from different fabric dyeing wastewaters using a pilot scale treatment system. A pilot scale system was installed in the wastewater outlet area of five different textile companies. Experiments were planned for pollutant removal and salt recovery from wastewater. First, the wastewater was treated by electrooxidation (EO) using graphite electrodes. After a reaction time of 1 h, the wastewater was passed throughout the granular activated carbon (AC) coloumn. The pre-treated wastewater was passed through the membrane (NF) system to recover the salt in the wastewater. Finally, the recovered salt water was used for fabric dyeing. In the pilot scale treatment system (EO + AC + NF), 100% of suspended solids (SS) and an average of 99.37% of color were removed from fabric dyeing wastewaters. At the same time, a high amount of salt water was recovered and reused. Optimum conditions were determined as 4 V current, 1000 A power, wastewater's own pH values and 60 min of reaction time. The energy and operating cost for treatment of 1 m3 of wastewater were determined as 40.0 kWh/m3 and 2.2 US$/m3, respectively. In addition to the prevention of environmental pollution by the treatment of wastewater using the pilot-scale treatment system, the reuse of the recovered water will contribute to the protection of our valuable water resources. In addition, using the NF membrane process after the EO system, it will be possible to recover salt from wastewater with high salt content such as textile wastewater.

Life cycle assessment of comparing different nutrient recovery systems from municipal wastewater: A path towards self-reliance and sustainability

Nutrient recovery systems can help to mitigate the negative effects of N and P in WW (wastewater), which when not recovered causes eutrophication in aquatic ecosystems. Using SimaPro (V9.3), the lifecycle assessment (LCA) of four nutrient recovery systems and sewage treatment plant (STP) were compared in this study. The findings showed that a fuel cell with a single-pot WW treatment system can function as a negative emission system with a global warming potential (GWP) of −234 gCO2 Eq./m3 of WW. Nutrient recovery reduces carbon footprint by 56–98% when compared to traditional fertilizers like diammonium phosphate (DAP) and urea. One of the main conclusions of this research was that single-pot systems perform better for the environment than add-on systems, which suggests that microalgae could perform better for the environment in a single-pot system. Recovering nutrients from WW not only improves self-reliance in the economy by decrementing the fertilizer import but also saves the environment.

Usability of brass and stainless steel electrodes in electrochemical treatment of 4-nitrophenol

4-Nitrophenol (4NP), which is used in many industries, is among the priority pollutants due to its carcinogenic, teratogenic, and mutagenic effects. In this study, the treatment of an aqueous solution containing 4NP was carried out by electrochemical method. A stainless steel electrode (Ss) allowing both electro-oxidation and electrocoagulation to occur together was used at the anode, while a brass (Bs) electrode with high conductivity was used at the cathode. By performing 4NP and total organic carbon (TOC) analyses on the samples taken from the reactor at certain times, the removal efficiencies and mineralization current efficiency (MCE) were determined. Based on the results, the optimum values of the operating parameters affecting the treatment efficiency were determined, the specific energy consumption (SEC) was calculated and the parameter-based statistical analysis of the data was performed. Under optimum conditions (pH: 5.5; Electrolyte: 3 g/L NaCl (5950 µs/cm); Current: 3.0 A (78 mA/cm2); Time: 20 min.; Distance: 0.5 cm), 97.44% 4NP and 33.09% TOC removal efficiencies were obtained. The energy consumption required to treat 1 m3 of wastewater electrochemically under these conditions was calculated as 28.37 kWh/m3. As a result of the statistical analysis, the most effective parameters in electrochemical treatment were determined as current, and time, respectively.

Water footprint of shale gas development in China in the carbon neutral era

The production of shale gas in China has repercussions for the global energy landscape and carbon neutrality. However, limited and threatened water resources may hinder the expansion of shale-derived natural gas, one of China's most promising development prospects. Coupling historical trends with policy guidance, we project that baseline water stress will intensify in two-thirds of China's provinces in the next decade. By 2035, annual water use for shale gas hydraulic fracturing activities is likely to increase to 16–35 million m3, with 13.8–23.7 million m3 of wastewater produced annually to extract 38–48 billion m3 of gas from ∼4800 shale gas wells. Analysis suggests that this projection is based on previously underestimated geological constraints (e.g., deep continental facies) in shale gas development in China. Nevertheless, forecasts suggest that the water footprint of shale development will become impossible to ignore, particularly in drought-stricken areas, indicating the potential risk of competition for water among shale development, domestic use, food production, and ecological protection. Meanwhile, the annual wastewater management market will increase to $0.2 billion by 2035. Our study suggests a critical need to direct attention to the (shale) energy-water nexus and develop multi-pronged policies to facilitate China's transition to carbon neutrality.

Treatment of laundry wastewater by different processes: Optimization and life cycle assessment

Wastewater from industrial laundries is often difficult to treat because it usually presents high turbidity and chemical oxygen demand (COD). We studied several processes for the treatment of laundry wastewater which was provided by a hotel in the south of Gran Canaria, Spain. More specifically, we studied coagulation with iron (III) sulphate, Fenton, photo-Fenton and a biological treatment (using a biofilter, and a granular activated carbon, GAC, filtration). The coagulation and Fenton processes produced large amounts of sludge and could not meet the required standards for water reuse in Spain. The use of photo-Fenton and the BF resulted in complete turbidity removal and high COD removal. However, we found that the effluent from the BF did not meet the COD removal criteria for water reuse, and thus a GAC filtration post-treatment was employed to reduce COD to acceptable levels. The photo-Fenton process alone did meet the criteria for water reuse. The estimated cost to treat 1 m3 of wastewater was 6.72 € for photo-Fenton and 0.71 € for BF + GAC. The cost and life cycle assessment analyses that were also performed revealed that the acquisition of the necessary reagents is the main contribution to the overall economic and environmental costs for both options, and that the BF + GAC option is notably cheaper. Additionally, this option also causes much lower environmental impacts than photo-Fenton.

A spherical fountain prototype photoreactor operated under natural sunlight: Mechanism, toxicology assessment, and economics

Many investigations have reported the study of dispersed nanoparticle photocatalysts on a laboratory scale. Herein, we present a working spherical fountain prototype photoreactor spray-coated with galvanic sludge to prevent agglomeration and increase surface activity. The degradation process was performed under natural sunlight to make the process sustainable. This photocatalytic reactor exhibited an efficiency of 90.4 % during the photodegradation of 4-Nitrophenol at the optimal conditions of a pollutant concentration of 25 ppm with a photocatalyst loading of 5 g at a natural pH for an operating volume of 7 L with an addition of 0.7 mL of H2O2. Detailed specific surface area, pore volume, pore diameter, shape, and agglomeration were studied by BET and HRTEM. There was a significant change observed in the morphology and crystallinity of the recycled photocatalyst, which could be due to photo-corrosion, as shown in the FESEM and XRD analyses. Moreover, a detailed mechanism was elucidated to understand the fate of 4-Nitrophenol during photodegradation. Furthermore, a toxicology assessment was conducted for the pollutant before and after degradation using Escherichia coli, which showed a decrease in the toxicity. Lastly, an economic evaluation was carried out to deduce the cost of treating 1 m3 of wastewater, which was determined to be USD 10.8/m3 for this photoreactor model.

Renewable Electricity and Hydrogen Production via Decentralized Wastewater Treatment Systems

Urban wastewater could be converted into energy if microbial electrochemical technologies (METs) like microbial dual-chamber electrolysis cells (MDEC) or microbial fuel cells (MFC) are applied as a treatment method. Mathematical modelling of MFC and MDEC for wastewater treatment and energy recovery has been developed in this study. The Radaue method has been used to solve ordinary differential equations (ODEs), and the model outputs were successfully validated with previous experimental and modelling data. A case study in Montreal, Canada, has also been considered for testing the application of METs on an urban scale with a total daily wastewater flow of 75,000 L/day. The results show that from 1 m3 of wastewater, MDEC and MFC can generate 0.077 kg H2 and 0.033 kWh, respectively.

Investigating phosphorus loads removed by chemical and biological methods in municipal wastewater treatment plants in Poland

The article presents an analysis of the current methods for phosphorus removal applied in municipal wastewater treatment plants in Poland. Within the study, 131 wastewater treatment plants were investigated, constituting 17 630 500 population equivalent, which is about 1/3 of the overall population equivalent (designed) in Poland. The research was based on a detailed technical questionnaire analysis obtained from wastewater treatment plants operators and calculations of pure metal doses in the applied coagulants and their type per a treated wastewater volume, population equivalent and phosphorus load removed. Moreover, a basic statistical analysis based on Pearson's correlation coefficient was applied to validate the relationship between the consumption of coagulants per the removed P load and the treated wastewater volume in 3 categories of wastewater treatment plants in terms of their population equivalent. The analysis results show that a minimum of 1470 Mg of phosphorus removed by 35 wastewater treatment plants based entirely on biological treatment methods could be used for phosphorus recovery to produce struvite, calcium phosphate or other highly bioavailable alternative fertilizer products. Moreover, 1490 Mg of phosphorus removed by other 17 wastewater treatment plants with a minimal coagulant dose (<1 g of metal per m3 of wastewater), increases the base for phosphorus recovery to approx. 2960 Mg per year using sewage sludge or its dewatering liquors. These results suggest that the implementation of the means mentioned above would significantly increase the possibilities for obtaining phosphorus from secondary sources, especially in wastewater treatment plants without sewage sludge incineration plants.

Preliminary Design Analysis of Membrane Bioreactors Application in Treatment Sequences for Modernization of Wastewater Treatment Plants.

By using modeling with the Capdetworks software package, the study examines the definition of the essential elements of operational expenses at wastewater treatment facilities with a capacity of 1 to 100 thousand cubic meters per day. Four different treatment sequences were examined in the study; the first three revealed a standard setup with an activated sludge reactor and secondary clarifier (operating under various operating conditions), and the fourth scheme combined an activated sludge reactor with a submerged membrane bioreactor for sludge separation. The values of concentrations of key pollutants common for urban wastewater before treatment as well as technological parameters of operation were utilized as initial data for calculations because it was crucial to obtain conclusions that could be applied at real facilities. For each of the four treatment sequences, values for pollutants concentrations in effluent wastewater and hydraulic retention time were obtained and analyzed. The expenses of operating biological treatment facilities and treatment facilities in general, as well as the specific cost of power for treating 1 m3 of wastewater, were taken into account. Additionally, the price of purchasing membrane modules, which can be categorized as operational due to their replacement frequency of around every 7 to 10 years, was determined. The study’s findings demonstrated that the use of membrane technologies at the secondary treatment stage might significantly affect the rebuilding of wastewater treatment plants under conditions of increased capacity (flow rate) and constrained area for growth.

Design and implementation of a treatment plant for the disposal of wastewater from portable toilets

Characterization of wastewater from portable toilets show parameters values (i.e., Chemical Oxygen Demand COD and total suspended solids TSS) that exceed the limits stablished by environmental regulations. This means that a prior treatment of these effluents is mandatory. This paper describes the design and construction of a plant for the treatment of wastewater from portable toilets, in a coastal city with dry/humid tropical weather conditions. The plant has a capacity for the treatment of 2.2 m3 of wastewater every two days. The batch process for the treatment of wastewater from portable toilets consists of primary treatment (screening and sedimentation), secondary treatment (biological activated sludge) and tertiary treatment (disinfection by chlorination, and filtration with activated carbon and gravel filters), in order to eliminate the chemical disintegrator of organic matter, the blue color, bacteria and odors, and to meet the limit values in discharges at surface water bodies and public sewerage system. Cleaner production strategies were also implemented to improve the sustainability of the process, such as the use of recycled material (i.e. the empty containers of agents for organic material disintegration), use of unevennes in the land to decrease energy consumption, use of equipment (tanks and filters) from disused production units and substitution of the toilet disinfectant (which was formaldehyde based disintegrator), for a biodegradable and non-toxic glutaraldehyde-based disinfectant, considering the environmental commitment involved in wastewater treatment processes. The characterization of the treated water from the plant showed that it can be discharged into the sewer. A characterization of the microbia present in the bioreactor is suggested for future research and optimization of the wastewater treatment plant, since the inoculum identified in the process will be a potential adjuvant in other processes for organic material degradation such as septic tanks and wastewater treatment plants located in similar climatic conditions.