Dilution Of Wastewater Research Articles

Treatment of molasses-based alcohol distillery wastewater using Electro-Fenton oxidation: Optimization and model prediction by response surface methodology

In this study, an Electro-Fenton process was employed to treat high-strength alcohol distillery wastewater. The simultaneously removal of chemical oxygen demand (COD), color, and turbidity were examined. The optimum value of the operational parameters including the number of electrodes and their arrangement, electrodes’ interval, initial pH, and electrolyte concentration were determined by one-factor-at-a-time (OFAT). The effect of essential parameters including current density, hydrogen peroxide concentration, and the duration of the process were optimized using response surface methodology (RSM). At fixed defined operational conditions by OFAT as four electrodes in a parallel arrangement with a 1 cm interval, 0.3 mol/L of electrolyte salt, and pH of 4, respectively, the optimal condition by RSM suggested the current density of 24 mA/cm2, 40 g/L of H2O2, and reaction time of 2 h. By adopting optimal condition at defined values of operational factors the removal efficiencies for COD, color, and turbidity were approximately 83%, 99%, and 97%, respectively, using fresh water for dilution. The energy consumption of 1.9 kWh/kg COD removal was achieved. Also, to save water, the treated wastewater (instead of fresh water) was used for the dilution of the raw wastewater, indicating the satisfactory results with removal efficiencies for COD, color, and turbidity of 71%, 94%, and 95%, respectively. Overall, the Electro-Fenton process is introduced as an appropriate process for treating high-strength alcohol distillery wastewater.

An Interdisciplinary Assessment of the Impact of Emerging Contaminants on Groundwater from Wastewater Containing Disodium EDTA

In recent years, there has been a surge in interest concerning emerging contaminants, also known as contaminants of emerging concern (CECs), due to their presence in environmental matrices. Despite lacking regulation, these chemicals pose potential health and environmental safety risks. Disodium EDTA, a widely utilized chelating agent, has raised concerns regarding its environmental impact. The present work aimed to verify the presence of Disodium EDTA at the exit of eight wastewater treatment plants discharging into some losing streams flowing within a large alluvial aquifer. Conducted in the Province of Parma (Northern Italy), the research employs a multidisciplinary approach, incorporating geological, hydrogeological, chemical, and microbial community analyses. Following a territorial analysis to assess industries in the region, through the use of ATECO codes (a classification system for economic activities), the study investigated the concentration of Disodium EDTA in effluents from eight diverse wastewater treatment plants, noting that all discharges originate from an activated sludge treatment plant, released into surface water courses feeding the alluvial aquifer. Results revealed detectable levels of Disodium EDTA in all samples, indicating its persistence post-treatment. Concentrations ranged from 80 to 980 µg/L, highlighting the need for further research on its environmental fate and potential mitigation strategies. Additionally, the microbial communities naturally occurring in shallow groundwater were analyzed from a hydrogeological perspective. The widespread presence of a bacterial community predominantly composed of aerobic bacteria further confirmed that the studied aquifer is diffusely unconfined or semi-confined and/or diffusely fed by surface water sources. Furthermore, the presence of fecal bacteria served as a marker of diffuse leakage from sewage networks, which contain pre-treated wastewater. Although concentrations of Disodium EDTA above the instrumental quantification limit have not been found in groundwater to date, this research highlights the significant vulnerability of aquifers to Disodium EDTA. It reveals the critical link between surface waters, which receive treated wastewaters impacted by Disodium EDTA, and groundwater, emphasizing how this connection can expose aquifers to potential contamination. At this stage of the research, dilution of wastewaters in surface- and groundwater, as well as hydrodynamic dispersion within the alluvial aquifer, seem to be the main factors influencing the decrease in Disodium EDTA concentration in the subsurface below the actual quantification limit. Consequently, there is a pressing need to enhance methodologies to lower the instrumental quantification limit within aqueous matrices. In a broader context, urgent measures are needed to address the risk of diffuse transport of CECs contaminants like Disodium EDTA and safeguard the integrity of surface and groundwater resources, which are essential for sustaining ecosystems and human health.

Approaches to substantiating the placement of industrial facilities within the sanitary protection zones of surface watercourses

Introduction. The article considers an approach to be used to delineate the source water protection area for the surface water bodies without putting manufacturing plants within the delineated areas out of action. The approach is based on the assessment of the disposals produced by plants on the water quality at the surface water intake point during the plant’s accident-free operation and both accidents within and beyond the design basis. Materials and methods. The article used the water protection area laws and regulations, the data observed of the disposal dispersion in the large rivers, and the original articles presented in databases and information systems: RSCI, CyberLeninka, Scopus, Web of Science. The solute transport analytical solutions for the dilution of the linear source in the flow serve as the methodological framework. Results. The article results have shown the local disposal into the river to form dispersion halo. Due to the specific dispersion processes, an area of a strip-like shape on the opposite shore can be formed where an anthropogenic influence is not present or negligible. This can be considered the background for the safe cooperative operation of the water intake and a manufacturing plant located within the water protection area. Limitations. The present article outlines the analytical approach for estimating the dilution of wastewater in river waters. The methodologies proposed are subject to several constraints, including the assumption of a constant river channel width and profile, steady discharge of contaminated wastewater, absence of water inflow losses or replenishment, lack of interaction with suspended particulate matter, uniform mixing across all segments of the river, and neglect of wind-induced effects on pollutant dispersion near the water surface. Failure to meet any of these assumptions necessitates recourse to more sophisticated numerical modelling techniques for accurate calculation. Conclusion. The use of the approach presented in the paper allows justifying the manufacturing plant’s operation within the source water protection area for the surface water bodies.

Winery wastewater treatment by microalgae Chlorella sorokiniana and characterization of the produced biomass for value-added products.

The microalgae Chlorella sorokiniana was used for the treatment of winery wastewater (WWW). Batch experiments were initially conducted to investigate how biomass acclimatization in different media, dilution of wastewater, and addition of ammonium nitrogen (NH4-N) affect the growth of microalgae and the removal of major pollutants. Afterwards, two sequencing batch reactor (SBR) systems were tested applying different configurations and hydraulic retention times. The biomass collected at the end of the experiments was characterized for proteins, lipids, carbohydrates, amino acid profile, and the existence of lutein, β-carotene, chlorophyll a, and tocopherols. Batch experiments showed that Chlorella sorokiniana acclimatization to urban wastewater enhanced the removal of NH4-N and total phosphorus (TP). The operation of a two-stage SBR system achieved COD and NH4-N removal equal to 85 ± 9% and 91 ± 20%, respectively, while the use of a single-stage system feeding with anaerobically pretreated WWW resulted to COD and NH4-N removal of 78 ± 9% and 95 ± 9%, respectively. Analyses of biomass showed higher protein content (up to 58.8%) in batch experiments with NH4-N addition as well as in SBR experiments. The cultivation of microalgae under SBR conditions enhanced the production of pigments and tocopherols. The maximum concentrations of 1075mgkg-1, 45.5mgkg-1, and 131.2mgkg-1 were achieved for lutein, β-carotene, and tocopherols, respectively, in the one-stage system. Our findings suggested that Chlorella sorokiniana cultivation in WWW not only removed nutrients from WWW but also could potentially serve for the production of value-added ingredients used in food industry, cosmetics, and animal feedstock.

Treatment of the Textile Wastewater using Malaysian Ganoderma lucidum Mycelial Pellets

Purification of textile wastewater using biomass and in particular different fungi is gaining exponential interest to minimize the impacts of current physical-chemical and biological wastewater treatment by-products. This study investigates the potential of Malaysian Ganoderma lucidum mycelium pellets (GLMP) for the decontamination of wastewater samples received from a commercial textile manufacturer. All studies were performed under ambient temperature (26-35 ℃) and unsterilized conditions using a simple bioreactor design (stirred batch bioreactor) for a more practical assimilation of the current available wastewater treatment process system. The optimal conditions of adsorption by GLMP were determined by variation effects of adsorbent concentration (0, 8.75, 12.5 and 25 g/L), pH (unadjusted 7.10 – 8.22, 4 and 6), and wastewater dilution factor (1:0, 1:4, and 2:3, v/v). This method was proved to be effective in both decolorization and chemical oxygen demand (COD) reduction, simultaneously. The most significant percentage of decolorization observed was 77.24% in a 72 h treatment, whereas COD reductions were 78.32% in a 36 h treatment. The present study fits both Langmuir and Freundlich adsorption isotherms as the values of R2 both model were close to 1, indicating the favorable adsorption of dyes towards Malaysian GLMP.

Magnesium hydroxide addition reduces aqueous carbon dioxide in wastewater discharged to the ocean

Ocean alkalinity enhancement (OAE) reduces the concentration of dissolved carbon dioxide (CO2) in seawater, leading to atmospheric carbon dioxide removal (CDR). Here we report laboratory experiments and a field-trial of alkalinity enhancement through addition of magnesium hydroxide to wastewater and its subsequent discharge to the coastal ocean. In wastewater, a 10% increase of average alkalinity (+0.56 mmol/kg) led to a 74% reduction in aqueous CO2 (−0.41 mmol/kg) and pH increase of 0.4 units to 7.78 (efficiency 0.73 molCO2/mol alkalinity). The alkalinization signal was limited to within a few metres of the ocean discharge, evident as 27.2 μatm reduction in CO2 partial pressure and 0.017 unit pH increase, and was consistent with rapid dilution of the alkali-treated wastewater. While this proof of concept field trial did not achieve CDR due to its small scale, it demonstrated the potential of magnesium hydroxide addition to wastewater as a CDR solution.

Use of aquaculture wastewater in the cultivation of cactus pear as an alternative for semi-arid regions

The objective was to characterize the dilutions of aquaculture wastewater in supply water and the morphometric and productive characteristics of the cactus pear. The experiment was installed at the Water Reuse Experimental Unit in Mossoró-RN, a Semi-Arid region of Brazil. The design was in randomized blocks with five treatments and five replications, being (D1—100% supply water; D2—75% supply water and 25% aquaculture wastewater; D3—50% supply water and 50% aquaculture wastewater; D4—25% supply water and 75% aquaculture wastewater; and D5—100% aquaculture wastewater). The physical–chemical characterization of the dilutions and the evaluation of the palm production and development parameters were carried out. The occupied area (Aop), the fresh volume of aerial phytomass (Vf), and the fresh weight of the aerial phytomass produced by the forage cactus (Pf) were estimated. The proportion of 75% aquaculture wastewater and 25% supply water provided the lowest average value for plant height in the analysis carried out over time and 365 days after planting. Variations in dilutions of aquaculture wastewater in supply water did not provide any difference in the plant's moisture content. Replacing supply water with aquaculture wastewater by up to 25% allowed productivity-like control.

Are the stream macrobenthos impacted by the wastewater from rubber factories?

We assessed how the wastewater generated from raw rubber factories affected the water quality parameters and how such changes influenced the stream macrobenthic assemblages in some streams in the wet zone of Sri Lanka. For this assessment, water quality parameters viz. DO, COD, BOD5, conductivity, TDS, T, pH, and OMC in the sediment were measured, and the macrobenthic fauna were sampled during the dry season at six sampling sites established based on judgemental sampling technique viz. rubber factory wastewater effluent canal (site A), point of wastewater discharge in the stream (site B), 50 m upstream site from site B (site C), 50 m downstream site from site B (site D), 100 m downstream site from site B (site E), and 150 m downstream site from site B (site F) following standard field sampling techniques. Secondary research data (dry season) from two other streams subjected to rubber factory wastewater effluents, namely Rakwatte Ela (2001) and Gurugoda Oya (2011), were also used for this assessment. Results revealed that the COD, BOD5, OMC, conductivity, and TDS levels were elevated, and the DO level was reduced significantly in the highly polluted A and B sites in all three streams. Parallel to them, the macrobenthic diversity decreased significantly (p<0.5; ANOVA) at these two sites. However, the complete opposite was observed at the furthermost downstream site F, where the water quality parameters and the microbenthic composition became almost the same as that in the upstream control site C. It is evident that the changes made to the stream water quality and the macrobenthic assemblages by the rubber factory wastewater are never permanent and disappear within a relatively short stretch of 150 m along the streams, most probably due to the dilution of wastewater along the stream. The pollution-tolerant tubificids and chironomids were bioindicator candidates to detect such changes where they became highly abundant at the highly polluted wastewater effluent canal (i.e., Site A) and point of wastewater discharge in the stream (i.e. Site B), but their abundance gradually decreased along the downstream sites probably due to wastewater dilution by the fresh water supply from the stream.

Home Sweet Home: Setting the Best Thriving Conditions for the Ad Hoc Engineered Microbial Consortium in the Zero Mile System

Wastewaters from household appliances, such as dishwashers and washing machines, are an untapped resource of recoverable water and/or nutrients. The Zero Mile system has been developed to reuse/upcycle dishwasher wastewaters through bioremediation activity carried out by an ad hoc engineered phototrophic/heterotrophic microbial consortium. The choice of both suitable microorganisms for engineering consortia and detailed knowledge on their structure, behaviour and interaction are essential to optimising consortium culture conditions and drive the biofilter container design (structure and topology). To these aims, the effect of abiotic conditions (i.e., irradiance, pH and organic load) on the microbial consortium growth and its capability to survive and thrive in different dishwasher wastewater dilutions have been evaluated. At the same time, the crucial interplay between biological and design research has allowed us to define the characteristics of the biofilter container and plan its development for the industrial application of the Zero Mile system, bringing sustainability benefits as it moves household wastewater from a traditional linear model to a more sustainable, circular approach.

Study of Shellfish Growing Area During Normal Harvesting Periods and Following Wastewater Overflows in an Urban Estuary With Complex Hydrography

Viral testing combined with hydrographic studies is considered standard good practice in determining microbiological impacts on shellfish growing areas following wastewater overflows. In this study, norovirus genogroup I and II, indicators of viral contamination (F-RNA bacteriophage genogroup II (F-RNA GII), crAssphage, pepper mild mottle virus) and Escherichia coli were monitored during periods of normal harvesting and following overflows in two commercial shellfish growing areas in Otago Harbour (Aotearoa New Zealand). Dye tracing, drogue tracking and analysis of particle tracking modelling were also undertaken to assess the dispersion, dilution and time of travel of wastewater discharged from a pump station discharge that impacts the growing areas. Norovirus was not detected in any of the 218 shellfish samples tested. PMMoV and crAssphage were more prevalent than F-RNA GII as determined by RT-qPCR. The dye study indicated long residence time of the waters (≥5 days) in the embayment impacted by the discharge. No relationships were found between the concentrations of viral indicators or E. coli and wastewater dilution, distance between the discharge and the growing areas or time since the last overflow. For the three spills studied (≤327 m3), there was little evidence of microbiological impact on the growing areas. This was likely associated with a deep shipping channel that enhances water flushing in the harbour and reduces contaminant transport to the growing areas. We recommend flexibility in the approach for closure/reopening growing areas impacted by spills, particularly for small duration/volume spills and when norovirus is not present in the community.

Evaluation of ecotechnology performance in treating textile wastewater: constructed treatment wetlands and natural adsorbents

The development of environmentally friendly technology for water ecosystem rehabilitation has become a challenge in solving pollution control problems in water bodies. Ecotechnology is a technology to improve water quality using an ecosystem approach, including the technology of constructed treatment wetlands and natural adsorbents. This study aims to produce an alternative ecotechnology for textile industrial waste remediation, on-site treatment of water bodies contaminated with textile waste, using a constructed treatment wetlands system and natural adsorbents. The result was conducted for 6 months using a reactor on a pilot scale with a continuous system. The result showed that CTWs’ ability effectively reduced ammonia in textile wastewater with a 20% dilution of up to > 80% and > 90% respectively using plants Vetiveria zizanioides and Heliconia psittacorum. Meanwhile, at 50% textile wastewater dilution, CTW with Heliconia psittacorum was more effective in reducing ammonia (> 80%) than CTW with Vetiveria zizanioides (> 60%). CTW with Vetiveria zizanioides and Heliconia psittacorum was able to reduce the dye content up to < 69.68% and < 54.39%, respectively. The natural adsorbent ability of bentonite has a higher ability to reduce dyes and ammonia, which is up to < 64.84% and < 91.12%. Good performance in these two eco-technology systems will result in better waste disposal by combining these two systems into one ecotechnology system.

Development of a national antibiotic multimetric index for identifying watersheds vulnerable to antibiotic pollution

Improved surveillance of antibiotics and antibiotic resistance (AR) throughout the environment is an important aspect of the prevention and control of threats posed to human and ecological health. In response to field investigations often limited by resources and time, this study aims to develop a systematic approach to assess watershed vulnerability to antibiotic pollution and AR by integrating modeling and field studies. The national antibiotic pollution vulnerability index was developed to identify watersheds most impacted by antibiotic sources. The index incorporates multiple metrics representing antibiotic pollution driven by both agricultural activities and municipal wastewater (i.e. outpatient antibiotic prescriptions, wastewater treatment plant effluent flow, stream order and dilution factor of effluent-receiving streams, manure application, and animal facilities), alongside climate change indicators (i.e., temperature, precipitation, and runoff). The pollution index was applied at a state level in North Carolina to identify the most-impacted watersheds and inform site selection for targeted field study quantifying azithromycin, ciprofloxacin, sulfamethoxazole, and trimethoprim concentrations. Modeled-informed sites in NC demonstrated the highest reported concentrations of azithromycin, trimethoprim, and sulfamethoxazole compared to previous NC studies, confirming the index effectiveness in identifying watersheds with higher antibiotic concentrations. At the national scale, watersheds relatively more vulnerable to antibiotic pollution are predominantly located in the Midwest, South, and Northeast regions of the U.S., with Iowa and Indiana being the most impacted states. Climate change is expected to exacerbate watershed vulnerability to agriculture-driven AR in the Midwest and Northeast due to an increase in precipitation and mean temperature coupled with intense agricultural activities. In addition, due to climate change-induced reductions in precipitation and runoff, watersheds in the Midwest, Mid-Atlantic, and South Central are dominantly at higher risk of effluent-driven AR occurrences. We have disseminated the developed indices as open-source online tools to aid in prioritizing strategies to mitigate AR occurrence across the U.S.

Cultivation of Chlorella pyrenoidosa and Scenedesmus obliquus in swine wastewater: Nitrogen and phosphorus removal and microalgal growth

Using microalgae to treat swine wastewater can effectively reduce the increasing pollution and save the cost of cultivating microalgae. In this study, the growth and denitrification and phosphorus removal effects of Scenedesmus obliquus and Chlorella pyrenoidosa at different dilutions in swine wastewater were investigated to solve the problem that microalgae could not be cultivated in the raw swine wastewater. After diluting the swine wastewater 8 and 12 times, the growth was optimized after 11 days of cultivation of Scenedesmus obliquus and 9 days of cultivation of Chlorella pyrenoidosa. Compared to Chlorella pyrenoidosa, the biomass and chlorophyll-a content were higher in Scenedesmus obliquus, at 1.48 g/L and 18.46 mg/L, respectively. The removal of nitrogen and phosphorus indicators was almost 100 %. Subsequently, Scenedesmus obliquus was cultured in an 8-fold dilution of swine and domestic wastewater, with dry weights of 0.83 g/L and 1.44 g/L, and lipid contents of 41.26 % and 25.11 %, respectively. Compared to Chlorella pyrenoidosa, Scenedesmus obliquus was more tolerant to nitrogen and phosphorus in swine wastewater, and at the same time, it had a higher growth rate, making it more suitable for treating swine wastewater and accumulating biomass.

Predicting wastewater treatment plant influent in mixed, separate, and combined sewers using nearby surface water discharge for better wastewater-based epidemiology sampling design

For wastewater sample collection approaches supporting public health applications, few high hydrologic activity normalizing guidelines currently consider readily available environmental flow data that may earlier capture information regarding periods of influent mixing and dilution of wastewater with groundwater and runoff. This study aimed to identify wastewater sampling rules for high hydrological activity events, allowing for an earlier decision point in the control of dilution before sample collection. We defined the sampling rules via data-driven models (Random Forest and linear regression) using environmental data (i.e., wastewater treatment facility influent rates, nearby stream discharge flow, and precipitation). These models were applied to five treatment plants in Jefferson County, Kentucky (USA) in mixed, separate, and combined sewers with different population sizes. We proposed cutoffs of 10 %, 25 %, and 50 % flow conditions for orientation towards public health samples. The results showed a strong nonlinear relationship between nearby stream discharge and treatment facility flow rates, which was used to infer the hydrological conditions that produce high volumes of diluted wastewater in the sewer system. Accumulated Local Effects and SHapley Additive exPlanations aided in deciphering the relationship between the predictors and response variables of the Random Forest models. The influent rate to the treatment plant from the previous day and two USGS stream gages were needed to adequately predict the degree of infiltration and inflow mixing on a given day. Surface water discharge data can be used to provide an earlier workflow decision point during wet weather periods to improve understanding of flow conditions for wastewater-based epidemiological studies to inform laboratory analysis and data interpretation. Not only total flow, but also the specific proportions of infiltration and inflow to wastewater volume in influent should be considered when analyzing data for normalization purposes, and our method provides a starting point for doing so rapidly and at low cost.

A One-Health environmental risk assessment of contaminants of emerging concern in London’s waterways throughout the SARS-CoV-2 pandemic

The SARS-CoV-2 pandemic had huge impacts on global urban populations, activity and health, yet little is known about attendant consequences for urban river ecosystems. We detected significant changes in occurrence and risks from contaminants of emerging concern (CECs) in waterways across Greater London (UK) during the pandemic. We were able to rapidly identify and monitor large numbers of CECs in n = 390 samples across 2019–2021 using novel direct-injection liquid chromatography-mass spectrometry methods for scalable targeted analysis, suspect screening and prioritisation of CEC risks. A total of 10,029 measured environmental concentrations (MECs) were obtained for 66 unique CECs. Pharmaceutical MECs decreased during lockdown in 2020 in the R. Thames (p ≤ 0.001), but then increased significantly in 2021 (p ≤ 0.01). For the tributary rivers, the R. Lee, Beverley Brook, R. Wandle and R. Hogsmill were the most impacted, primarily via wastewater treatment plant effluent and combined sewer overflows. In the R. Hogsmill in particular, pharmaceutical MEC trends were generally correlated with NHS prescription statistics, likely reflecting limited wastewater dilution. Suspect screening of ∼ 1,200 compounds tentatively identified 25 additional CECs at the five most impacted sites, including metabolites such as O-desmethylvenlafaxine, an EU Watch List compound. Lastly, risk quotients (RQs) ≥ 0.1 were calculated for 21 compounds across the whole Greater London freshwater catchment, of which seven were of medium risk (RQ ≥ 1.0) and three were in the high-risk category (RQ ≥ 10), including imidacloprid (RQ = 19.6), azithromycin (15.7) and diclofenac (10.5). This is the largest spatiotemporal dataset of its kind for any major capital city globally and the first for Greater London, representing ∼ 16 % of the population of England, and delivering a foundational One-Health case study in the third largest city in Europe across a global pandemic.

Evaluation of four human-associated fecal biomarkers in wastewater in Southern Ontario

Human fecal biomarkers (HFBs) have a longstanding history in the field of microbial source tracking (MST) serving as indicators of human fecal contamination in drinking and recreational water. Further, HFBs have aided in recent efforts to monitor human pathogen transmission within communities. The dilution of wastewater from various sources throughout the sewershed cannot be controlled and human fecal biomarkers (HFBs) can be used to normalize target human pathogen concentrations so that fluctuations in fecal matter in wastewater can be accounted for. In the current study, we monitored the prevalence of four HFBs – including two viruses, Pepper mild mottle virus (PMMoV), cross-assembly phage (crAssphage), as well as two human-associated Bacteroides markers, HF183 and BacHuman - in wastewater samples from ten Southern Ontario wastewater treatment plants and evaluated their temporal and spatial variation in context of environmental factors that may impact the ability of HFB to normalize pathogen concentrations in wastewater. Environmental variables including precipitation, wastewater flow rate, temperature, and concentrated mass were also analyzed for their potential correlation with HFB variation in wastewater. The four HFBs were detected at high concentrations across all 10 sampling locations. The median concentrations across all sampling sites were: PMMoV 3.6 Log gene copies (GC)/mL; crAssphage 5.0 Log GC/mL; HF183 6.8 Log GC/mL and BacHuman 6.9 Log GC/mL. All HFBs were found to be similarly stratified across all 10 sites, and the bacterial markers were consistently found at higher concentration compared to the viral HFBs at all sites. The coefficient of variation (CV) for each HFB was used to characterize the variability of each biomarker at each sewershed. BacHuman and crAssphage were found to have lower CV than PMMoV and HF183, indicating that BacHuman and crAssphage may perform better in reflecting the variations in abundance of human feces in wastewater or MST applications.

Biodiesel Production from the Marine Alga Nannochloropsis oceanica Grown on Yeast Wastewater and the Effect on Its Biochemical Composition and Gene Expression.

Microalgae-based biodiesel synthesis is currently not commercially viable due to the high costs of culture realizations and low lipid yields. The main objective of the current study was to determine the possibility of growing Nannochloropsis oceanica on Saccharomyces cerevisiae yeast wastewater for biodiesel generation at an economical rate. N. oceanica was grown in Guillard F/2 synthetic medium and three dilutions of yeast wastewater (1, 1.25, and 1.5%). Biodiesel properties, in addition to carbohydrate, protein, lipid, dry weight, biomass, lipid productivity, amino acids, and fatty acid methyl ester (FAMEs) content, were analyzed and the quality of the produced biodiesel is assessed. The data revealed the response of N. oceanica to nitrogen-deficiency in the three dilutions of yeast wastewater. N. oceanica in Y2 (1.25%) yeast wastewater dilution exhibited the highest total carbohydrate and lipid percentages (21.19% and 41.97%, respectively), and the highest lipid productivity (52.46 mg L-1 day -1) under nitrogen deficiency in yeast wastewater. The fatty acids profile shows that N. oceanica cultivated in Y2 (1.25%) wastewater dilution provides a significant level of TSFA (47.42%) and can be used as a feedstock for biodiesel synthesis. In addition, N. oceanica responded to nitrogen shortage in wastewater dilutions by upregulating the gene encoding delta-9 fatty acid desaturase (Δ9FAD). As a result, the oleic and palmitoleic acid levels increased in the fatty acid profile of Y2 yeast wastewater dilution, highlighting the increased activity of Δ9FAD enzyme in transforming stearic acid and palmitic acid into oleic acid and palmitoleic acid. This study proved that the Y2 (1.25%) yeast wastewater dilution can be utilized as a growth medium for improving the quantity of specific fatty acids and lipid productivity in N. oceanica that affect biodiesel quality to satisfy global biodiesel requirements.

Screening of wastewater Oedogonium oblangum algae for hyper-oil transformation into biodiesel by response surface methodology

The algae have gained more significance as a renewable third-generation feedstock for being easily available and a hyper-production source for lipids and biodiesel. Sustainable and cost-effective production of algal biodiesel requires screening and optimization of various culture conditions. Screening of algae on the basis of its lipid content is crucial for exploring its potential for production of biodiesel. In the current study, the screening of six indigenous algal strains was performed based on lipid contents, out of which Oedogonium oblangum (O. oblangum) exhibited hyper-lipid content (15.76%). Bold basal media and wastewater media were compared as culture media to evaluate the growth of O. oblangum; the respective strain showed better growth on wastewater media, therefore, this media was used for further experimentation. A laboratory-based integrated approach was used to enhance production of algal lipids by applying the effects of temperature, pH, and wastewater dilutions. The oil contents were interestingly improved under the optimal culture conditions of temperature (25°C), pH (6.5), wastewater dilution (45%) with oil contents of 18.35%, 17.15%, and 17.95%, respectively. The extracted oil was transformed into biodiesel by alkali-mediated transesterification reactions using four factors (Oil/methanol ratio, temperature, time, and catalyst) by response surface methodology (RSM). The RSM successfully optimized the transesterification reactions with 86.73% of biodiesel under optimal conditions of oil/alcohol ratio (1:7.6 v/v), temperature (60.5°C), time (59 ​min), and catalyst (0.53 ​wt. %). Physical properties of biodiesel (kinematic viscosity; 5.17; acid value; 0.63; flash point; 152; specific gravity; 0.74; calorific value; 42.11; and water contents; 0.03) comply with the ASTM standards and lead to enhance the quality of produced biodiesel. The optimized culture conditions, transesterification reactions, and wastewater medium can be employed for the economically production of biodiesel at commercial scale. Overall, the results showed that biodiesel derived from an indigenous novel algal strain, O. oblangum, has the potential to compete and replace commercially available petro-diesel using wastewater media. It might contribute to resolve the energy challenges being faced by Pakistan and the entire world.

Cultivation of Spirulina platensis for nutrient removal from piggery wastewater.

The discharge of livestock wastewater without appropriate treatment causes severe harm to the environment and human health. In the pursuit of finding solutions to this problem, the cultivation of microalgae as feedstock for biodiesel and animal feed additive using livestock wastewater coupled with the removal of nutrients from wastewater has become a hot research topic. In this study, the cultivation of Spirulina platensis using piggery wastewater for the production of biomass and the removal of nutrients were studied. The results of single factor experiments confirmed that Cu2+ seriously inhibit the growth of Spirulina platensis, while the influences of nitrogen, phosphorous, and zinc on the growth of Spirulina platensis can all be described as "low promotes high inhibits." Spirulina platensis grew well in the 4-fold dilution of piggery wastewater supplemented with moderate sodium bicarbonate, which indicated that it is the limiting nutrients for Spirulina platensis growth in piggery wastewater. The biomass concentration of Spirulina platensis reached 0.56g/L after 8days of culture at the optimal conditions proposed by the response surface method, which were as follows: 4-fold dilution of piggery wastewater, 7g/L sodium bicarbonate, pH of 10.5, initial OD560 of 0.63, light intensity of 3030lx, and light time/dark time of 16h/8h. Spirulina platensis cultured in the diluted piggery wastewater contained 43.89% protein, 9.4% crude lipid, 6.41mg/g chlorophyll a, 4.18% total sugar, 27.7mg/kg Cu, and 246.2mg/kg Zn. The removal efficiency for TN, TP, COD, Zn, and Cu from the wastewater by Spirulina platensis was 76%, 72%, 93.1%, 93.5%, and 82.5%, respectively. These results demonstrated the feasibility of piggery wastewater treatment by the cultivation of Spirulina platensis.

Raman spectroscopy and XRF identification: First step in industrial wastewater management

Considering the environmental risk, industrial facilities should strive to maximise the effectiveness of on-site treatment processes. It is important to detect the types of pollutants in wastewater and their concentrations, which can be challenging in industrial conditions. In this study, industrial wastewater samples from pickling and electropolishing of stainless steel were analyzed through Raman spectroscopy and XRF techniques using portable instruments. A 3-step procedure for the rapid identification of type of wastewater was proposed. The identification and analysis of peaks present in the Raman spectroscopy at 900, 990, 1050, 1380 cm−1allows for the differentiation of wastewater type and dilution. The final step is to employ XRF measurements to determine the approximate content of the investigated elements. The use of portable analytical instruments for the estimation of contamination levels is essential for the management of the industrial wastewater neutralization process as well as during emergency operations in cases of accidents.