Engineering Hydroponic Systems for Sustainable Wastewater Treatment and Plant Growth

This study aimed to optimize hydroponic systems for simultaneous wastewater treatment/nutrient recovery and plant growth. Various hydroponic systems (geyser pump, full flow, ebb and flow, nutrient film techniques, aeroponics, misting) were constructed using 160 mm PVC waste pipes supported on a 200 L reservoir. Secondary wastewater was used to cultivate rice (Oryza sativa), ivy (Hedera helix), tomatoes (Solanum lycopersicum), and wheatgrass (Triticum aestivum). Parameters such as plant height, biomass, retention time, temperature, conductivity, pH, dissolved oxygen, ammonia, nitrite, nitrate, total phosphorus, COD, BOD, TDS, TSS, and TS were monitored. Results indicated minor variations in pH, EC, and TDS over time in systems with and without plants, with no significant differences. Turbidity decreased significantly (p ≤ 0.001) in all systems, while TOC levels reduced significantly (p ≤ 0.05) only in the presence of plants. BOD and COD levels exhibited similar reductions with and without plants. Ammonium levels decreased in plant systems, while nitrite levels remained unchanged. Nitrate levels increased significantly in plant systems, and phosphate levels showed no significant difference. Additionally, significant (p ≤ 0.001) plant length (12.84–46.75%) and biomass (31.90–57.86%) increases were observed in all hydroponic systems, accompanied by higher levels of dissolved oxygen (36.26–53.65%), compared to the control (4.59%). The hydroponic system that created a moist atmosphere, either through misting or aeroponics, thus allowing maximum access to oxygen, showed the greatest growth. This study confirmed the importance of oxygen availability to the rhizosphere for plant growth and wastewater treatment. It also identified limitations and investigated the impact of dissolved oxygen concentration on plant–microorganism interactions. Optimal oxygen availability was achieved when plant roots were exposed to a moist atmosphere created by the hydroponic system through aeroponics or misting. The findings have practical implications for hydroponic system design in urban vertical farms, benefiting wastewater treatment, mitigating eutrophication, and reducing food miles

Assessing the vulnerability of agriculture systems to climate change in coastal areas: A novel index

This study proposes a novel index to evaluate agricultural vulnerability to climate change in coastal areas, using the case of Andhra Pradesh, the state with the second longest coastline in India. Field data was collected from more than 1000 farmers (involved in over 50 varieties of crops) in 22 riverine and coastal case study areas. Data was collected through site visits, surveys and five workshops conducted between November 2018 and June 2019. Based on the collected data sets, a new Agricultural Coastal Vulnerability Index (AGCVI) was developed and applied to the 22 sites located in two districts (Krishna and Guntur) of Coastal Andhra Pradesh. The analysis revealed that the areas with three crop seasons (Kharif, Rabi and Zaid) per year are highly vulnerable to climate change. On the other hand, sites with one crop season (Kharif) per annum are the least vulnerable to climate change. Moreover, grains (particularly rice), flowers and fruit crops are more susceptible to climate change and its induced impacts. Rice is no longer a profitable crop in the case study areas partly as a result of unfavourable weather conditions, inadequate insurance provision and lack of government support for farmers. Cumulatively, all these circumstances impact farmers’ incomes and socio-cultural practices: this is leading to a marriage crisis, with a reduction in the desirability of matrimony to farmers. These findings provide valuable information that can support climate and agriculture policies, as well as sustainable cropping patterns among farmers’ communities in coastal areas of India in the future

Photodegradation of free estrogens driven by the UV light: Effects of operation mode and water matrix

Estrogens are endocrine disrupting chemicals that have been frequently detected in diverse water matrices (e.g. surface water, wastewater and drinking water) and caused a series of health risks. This study was aimed at investigating the photochemical degradation of free estrogens estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethyl estradiol (EE2) upon the monochromatic irradiation (253.7 nm). Concerning the practical installation of photolysis treatment, exposing the impacts of photoreactor operation mode (stationary or up-flow) and the water matrix (ultrapure water or natural surface water) on the photolytic behaviour of estrogens was of high importance. The pseudo-first-order rate constants showed that E1 was the most susceptible to UV radiation among chosen estrogens due to its high molar absorption coefficient of 402.4 M^{−1] cm^{−1} and quantum yield of 0.065 mol E^{−1} at λ = 253.7 nm. Moreover, the up-flow mode and the surface water matrix collected from a lake in Regent's Park (London) were found to favour the photodegradation of estrogens due to the introduction of more dissolved oxygens and promotion of reactive oxygen species (ROS) formation. These findings may shed light on the photochemical behaviour of estrogens in some specific scenarios

Algae, biochar and bacteria for acid mine drainage (AMD) remediation:A review

Acid mine drainage (AMD) is a global issue and causes harmful environmental impacts. AMD has high acidity and contains a high concentration of heavy metals and metalloids, making it toxic to plants, animals, and humans. Traditional treatments for AMD have been widely used for a long time. Nevertheless, some limitations, such as low efficacy and secondary contamination, have led them to be replaced by other methods such as the bio-based AMD treatments. This study reviewed three bio-based treatment methods using algae, biochar, and bacteria that can be used separately and potentially in combination for effective and sustainable AMD treatment to identify the removal mechanisms and essential parameters affecting AMD treatment. All bio-based methods, when applied as a single process and in combination (e.g. algae-biochar and algae-bacteria), were identified as effective treatments for AMD. Also, all these bio-based methods were found to be affected by some parameters (e.g. pH, temperature, biomass concentration and initial metal concentration) when removing heavy metals from AMDs. However, we did not identify any research focusing on the combination of algae-biochar-bacteria as a consortium for AMD treatment. Therefore, due to the excellent performance in AMD treatment of algae, biochar and bacteria and the potential synergism among them, this review provides new insight and discusses the feasibility of the combination of algae-biochar-bacteria for AMD treatment

Effect of organic matter release from natural cork used on bisphenol a removal from aqueous solution

The paper presents an experimental study aimed at investigating the mechanism responsible for Bisphenol A adsorption on natural cork, and the role played on process kinetics by the organic matter released from the cork. Obtained data show that natural cork has a good affinity toward Bisphenol A, with removal efficiency being as high as 75% in less than 24 h. The adsorption process is characterized by a fast-initial rate which tends to reduce progressively, and follows a pseudo second order model equation. Statistical physics analysis allows for obtaining a molecular description of the adsorption, which is shown to take place through a single anchorage point, perpendicularly to the adsorbent surface. Nuclear magnetic resonance spectroscopy and fluorescence analysis reveal that the colloidal organic matter released from the cork interacts with Bisphenol A; it also plays a relevant role in the slowing down of the adsorption rate, as it competes with cork adsorption sites for Bisphenol A. Organic matter is found to be highly heterogenous, presenting at the same time carbohydrates, aromatic and aliphatic domains. Such moieties interact stably with the contaminant in the solution probably due the establishment of dispersive forces (e.g. π-stacking) which sequestrate Bisphenol A into the inner hydrophobic core of the organic matter three-dimensional structure

Strength assessment of Al-Humic and Al-Kaolin aggregates by intrusive and non-intrusive methods

Made available in DSpace on 2019-10-06T15:34:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-15Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Resistance to breakage is a critical property of aggregates generated in water and wastewater treatment processes. After flocculation, aggregates should ideally keep their physical characteristics (i.e. size and morphology), to result in the best performance possible by individual separation processes. The integrity of aggregates after flocculation depends upon their capacity to resist shear forces while transported through canals, passages, apertures, orifices and other hydraulic units. In this study, the strength of Al-Humic and Al-Kaolin aggregates was investigated using two macroscopic measurement techniques, based on both intrusive and non-intrusive methods, using image analysis and light scattering based equipment. Each technique generates different information which was used for obtaining three floc strength indicators, namely, strength factor (SF), local stress from the hydrodynamic disturbance (σ) and the force coefficient (γ) for two different study waters. The results showed an increasing trend for the SF of both Al-Humic and Al-Kaolin aggregates, ranging from 29.7% to 78.6% and from 33.3% to 85.2%, respectively, in response to the increase of applied shear forces during flocculation (from 20 to 120 s−1). This indicates that aggregates formed at higher shear rates are more resistant to breakage than those formed at lower rates. In these conditions, σ values were observed to range from 0.07 to 0.44 N/m2 and from 0.08 to 0.47 N/m2 for Al-Humic and Al-Kaolin, respectively. Additionally, it was found that for all studied conditions, the resistance of aggregates to shear forces was nearly the same for Al-Humic and Al-Kaolin aggregates, formed from destabilized particles using sweep coagulation. These results suggest that aggregate strength may be mainly controlled by the coagulant, emphasizing the importance of the coagulant selection in water treatment. In addition, the use of both intrusive and non-intrusive techniques helped to confirm and expand previous experiments recently reported in literature.Instituto de Geociências e Ciências Exatas Univ. Estadual Paulista (UNESP), Av. 24-A, 1515, Jardim Bela Vista, Rio ClaroPrograma de Pós-graduação em Engenharia Civil e Ambiental Univ. Estadual Paulista (UNESP), Av. 24-A, 1515, Jardim Bela Vista, Rio ClaroDepartment of Civil Engineering University of BirminghamDepartment of Civil Environmental and Geomatic Engineering University College London, Gower StInstituto de Geociências e Ciências Exatas Univ. Estadual Paulista (UNESP), Av. 24-A, 1515, Jardim Bela Vista, Rio ClaroPrograma de Pós-graduação em Engenharia Civil e Ambiental Univ. Estadual Paulista (UNESP), Av. 24-A, 1515, Jardim Bela Vista, Rio ClaroFAPESP: 2017/19195-

Real-time flood overflow forecasting in Urban Drainage Systems by using time-series multi-stacking of data mining techniques

© 2023 The Author(s).Overflow forecasting in early warning systems is acknowledged as an essential task for devastating urban flood risk management. Although many machine learning models have been developed recently to forecast water levels in urban drainage systems (UDS), they usually require big and accurate data resources [1]. Alternatively, ensemble data mining models are becoming more popular, in which time-series numerical data are turned into the categorised features that classify wet weather conditions as two classes of overflow and non-overflow conditions [2]. However, the concept of time-series ensemble modelling i.e., blending different data mining techniques for predictions with different timesteps is still new [3]. Furthermore, the application of more advanced models, particularly multi-blending in these types of ensemble modelling requires more investigation. This study aims to introduce a novel multi-stacking model that integrates different decision tree frameworks by developing various base weak learner data mining techniques and associated base model performance indicators in the process of time-series blending of pre-trained stacked ensemble models. The performance of this new approach is compared by several previously developed ensemble models [2] through confusion matrix performance criteria, including hit rate, overestimation, and underestimation. This method is demonstrated by its application to a real case study of UDS located in the northwest of London for performance assessment up to 5hr ahead (i.e., 20 timesteps with 15-min intervals). In total, 140 base-models and 20 stacked models were developed that are stored in the data warehouse to use as real-time early-warning flood overflow forecasting for this case study. These developed models were used through introduced decision three framework that specified stacking blending methodology. Results show that while base models and stacked models suffer from high miss rate, especially for forecasting more than 3hrs ahead (more than 50%), the proposed multi-stacking model could perfectly maintain the miss rate (i.e., sum of over- and under-estimations) of up to 4hr-ahead predictions less than 10%, but this rate dropped to nearly 30% for 5hr-ahead predictions. However, the rate of overflow forecasting remained acceptably near 80% whereas it is recorded to less than 58% for other benchmark models. Using different decision frameworks for determining importance of each stacked model in blending mode of multi-stacking method shows could reduce errors in forecasting rate and take advantage of each model in real-time early warning urban flood forecasting.Peer reviewe

Efficiency of Treated Domestic Wastewater to Irrigate Two Rice Cultivars, PK 386 and Basmati 515, under a Hydroponic Culture System

The increasing human population continues to exert pressure on the freshwater scarcity. The availability of freshwater for crop irrigation has become challenging. The present study aimed to use domestic wastewater (DWW) for the irrigation of two rice cultivars (CVs) after treatment with the bacterial strain Alcaligenes faecalis MT477813 under a hydroponic culture system. The first part of this study focused on the bioremediation and analysis of the physicochemical parameters of DWW to compare pollutants before and after treatment. The biotreatment of DWW with the bacterial isolate showed more than 90% decolourisation, along with a reduction in contaminants. The next part of the study evaluated the impacts of treated and untreated DWW on the growth of two rice cultivars, i.e., PK 386 and Basmati 515, under a hydroponic culture system which provided nutrients and water to plants with equal and higher yields compared to soil. Growth parameters such as the shoot and root length and the wet and dry weights of the rice plants grown in the treated DWW were considerably higher than those for the plants grown in untreated DWW. Therefore, enhanced growth of both rice cultivars grown in biotreated DWW was observed. These results demonstrate the bioremediation efficiency of the bacterial isolate and the utility of the DWW for rice crop irrigation subsequent to biotreatment

Investigating how COVID-19 has challenged the Eurocentric concept of ‘development’: a case for sustainable food systems in the UK

The COVID-19 health crisis has imposed extensive shocks to many global systems, particularly the UK food production chains, further challenging Eurocentric development discourses and stereotypes. Thus, this paper investigates how the pandemic has challenged the UK's development status by analysing how the pandemic has impacted the country's food industry. A literature review was conducted and used to identify, select and critically appraise publications between 2000 and 2021 discussing the challenges in the UK food system. The findings reveal that the UK's food industry is unsustainable as there are significant flaws in the system, that is food insecurity and food waste that go unaddressed. The impact of the pandemic has exacerbated the social and economic impacts of operating with such a system. Compounded with the geopolitical adjustments caused by Brexit, the UK is faced with the challenge of restructuring and developing new frameworks such as policies, regulations, schemes and partnerships to support the food industry's sustainability. Lastly, the findings reinforce that ‘developed’ and ‘developing’ nations encounter similar food challenges, which manifest differently in various landscapes and contexts. Therefore, the world (not just the UK) needs to shift away from Eurocentrism, moving towards a universal but equally personalised development outlook. This review provides an outline of the major problem areas in the UK food system and presents potential solutions aimed at helping guide the government's decision-making process

Assessment of microplastics in freshwater systems : a review

The reliance on plastic for a vast number of consumer products, many of them single-use, results in their continuous entry into aquatic environments. Plastic waste can fragment into smaller debris, some with diameter <5 mm (microplastics). Microplastics have been of growing concern especially since 2014, however to date research on microplastic pollution has mainly focused on marine environments, partly because it has been mistakenly thought that sewage treatment plants could remove all plastic debris. To understand the impact of microplastic pollution in freshwater environments, an assessment of research on the sources, distribution and effects of microplastics, and trends in their analysis and policy has been carried out. The main sources of microplastic found in freshwater environments include synthetic textiles, personal care products, industrial raw materials and the improper disposal of plastic waste. Microplastic pollution is a global issue that presents with a broad range of concentration: for example, 3.5 x 10^3 microplastic units·L-1 were reported in sediment of Lake Huron, the US and as low as 1.2×10-4 units·L-1 in countries with sparse population such as Mongolia. The main polymer constituents of microplastics found in freshwaters have been identified as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET), accounting for 70% of the total, each with a very similar frequency of occurrence. Despite microplastics being relatively inert, they are found to cause some effects in aquatic organisms. Future work should focus on monitoring microplastic pollution in regions from where there is currently scarce published data (e.g. South America, Africa and North Asia) and the study of their sources, stability, transport and effects to freshwater ecosystems. The establishment of standardized monitoring methods will allow for the comparison of data from different geographic areas. This information will inform measures to reduce the release and occurrence of microplastics in aquatic environments