Combined organic coagulants and photocatalytic processes for winery wastewater treatment

Effective reduction of carbon-containing pollutants in coffee cherry pulping wastewater using natural polysaccharide from Tamarindus indica L. seeds

The wastewater produced during coffee cherry pulping is known for containing harmful pollutants, particularly organic compounds containing carbon, which pose significant risks to the environment and human health. This research aimed to evaluate the effectiveness of Tamarindus indica L. seed polysaccharides in treating coffee effluent. Varying doses (ranging from 0.05 to 0.30 g) of the isolated polysaccharides were added to samples of the effluent to determine their ability to remove contaminants, especially those of organic carbon origin. Notably, a dosage of 0.10 g demonstrated optimal efficacy, resulting in a 55% decrease in total dissolved solids and an 80% decrease in chemical oxygen demand. Additionally, Fourier-transform infrared and zeta potential analysis of both the polysaccharides and the treated effluent samples revealed the presence of functional groups potentially pivotal for the pollutant removal activity of the isolated polysaccharides. This provides insights into the coagulation mechanism of Tamarindus indica L. seed polysaccharides in eliminating organic carbon-based pollutants. These findings highlight the potential of Tamarindus polysaccharides as a sustainable alternative to chemical agents for removing pollutants, thus promoting environmental sustainability and human well-being.

Energy efficiency in winemaking industry: Challenges and opportunities

The United Nations has issued a warning over the limited time for climate disaster prevention. In the last two decades, several countries have set targets to reduce fossil fuel usage and greenhouse gas emissions. These goals are tracked through the adoption of energy systems that prioritise efficiency and low-carbon alternatives, in alignment with the Sustainable Development Goals outlined by the United Nations. In the winemaking sector, the wine produced in the European Union comprised 65 % of the worldwide total from 2014 to 2018, with vineyards making up 4.7 % of its farms in 2020. Electricity is the primary source of energy used in vineries, accounting for around 90 % of the total energy consumption. The energy consumption associated with winemaking is mostly attributed to two key processes: fermentation, which accounts for 45 % to 90 % of the entire energy consumption, and bottling and storage, which contribute around 18 % of the overall energy consumption. The aim of this article is to provide an integrated review of energy efficiency in wineries through examining 144 academic publications. The selected publications cover various aspects, including sustainable energy utilisation in the wine industry, thermal performance analysis of buildings, energy efficiency assessment of systems and technologies, and the integration of renewable energy sources. A link has been established between the geographic distribution of academic publications and wine-producing countries. In relation to European publications, it is observed that research funding is associated with the energy directives of the European Union. It can also be concluded that wine customers are pushing for environmentally friendly practices. However, not everyone in the winemaking sector is moving in the same direction or at the same pace. To identify areas for improvement, winemakers must have supporting tools to manage energy use. Systems optimisation, monitoring, and accounting can be used to decrease energy consumption in winemaking processes or equipment. Progresses on sustainable energy use through greater energy efficiency and share of renewable energies in the wineries can contribute to the reduction of greenhouse gas emissions, and consequently, brings the wine industry closer to climate neutrality.

Winery and olive mill wastewaters treatment using nitrilotriacetic acid/UV-C/Fenton process: Batch and semi-continuous mode

In this work, both red and white winery wastewaters (WW) and olive mill wastewater (OMW) were submitted to a treatment by Fenton-based processes (FBPs). The main aim was to evaluate the most efficient and economic process. Initial tests, resorting to a batch reactor, demonstrated that UV-C/Fenton (λ = 254 nm) was the most effective process. Operational conditions such as pH, H2O2 and Fe2+ concentrations revealed to have a superior influence within dissolved organic carbon (DOC) removal as well as regarding the reactor's energy consumption. As a means to prevent iron precipitation, the addition of nitrilotriacetic acid (NTA) was tested. With experimental conditions pH = 3.0, [H2O2] = 194 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), time = 240 min, the kinetic rate related with DOC removal showed a kredWW = 0.0128 min-1 > kOMW = 0.0124 min-1 > kwhiteWW = 0.0104 min-1 and both the WW and OMW achieved the Portuguese legal limit values for wastewater discharge. Furthermore, comparative experiments were performed in a semi-continuous reactor, being that the results put in evidence that the concentration of H2O2 added and the flow rate of reagents' addition (F) had a significant effect on the efficiency of the reactor. Under an optimum experimental procedure pH = 3.0, [H2O2] = 97 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), F = 1 mL min-1, time = 240 min, there were observed higher DOC removal kinetic rates (kOMW = 15.20 × 10-3 min-1 > kredWW = 11.64 × 10-3 min-1 > kwhiteWW = 11.57 × 10-3 min-1) and a cost ranging between 0.0402 and 0.0419 €/g.DOC. These results showed that semi-continuous reactors have the potential to be applied to large scale treatments, with low reagents consumption and reduced energy requirements.

Enhancement of EDDS-photo-Fenton process with plant-based coagulants for winery wastewater management

To achieve an efficient remediation of a winery wastewater (WW), it was studied a physical-chemical process (coagulation-flocculation-decantation - CFD) involving plant-based coagulants (PBC) with advanced oxidation processes (AOPs), aiming to achieve the Portuguese legal limits. Initially, one invasive (Acacia dealbata) and three native species (Quercus ilex, Platanus x acerifólia and Tanacetum vulgare) were collected and used as plant-based coagulants (PBCs). The combination of Platanus acerifólia (P.a.) seeds with polyvinylpolypyrrolidone (PVPP) achieved high turbidity (97.3%) and chemical oxygen demand (COD = 48.2%) removals, from raw WW, with [PBC] = 0.1 g/L, [PVPP] = 5 mg/L, pH = 3.0, fast mix = 150 rpm/3 min, slow mix = 20 rpm/20 min, sedimentation time = 12 h. Different AOPs were studied to treat raw WW, with photo-Fenton process revealing the highest COD efficiency (88.0%). To enhance the capabilities of photo-Fenton, ethylenediamine-N,N'-disuccinic acid trisodium salt (EDDS) was assessed as a chelation agent, reducing iron precipitation. The pre-treatment of WW by PBCs followed by EDDS/photo-Fenton (pH = 6.0, [H₂O₂] = 175 mM, [Fe²⁺] = 5 mM, [EDDS] = 1 mM, T = 298 K, time = 240 min) increased the COD removal, whatever the radiation source applied (UV-C, UV-A and solar). Among the different processes, the combined P. a. seeds and UV-C/EDDS/Fenton allowed increase the WW biodegradability from 0.26 to 0.46, and achieved a COD removal of 95.7%, reaching the Portuguese legal limits. As final remark, the synergy of PBCs and EDDS/photo-Fenton is considered effective and sustainable process for raw WW remediation and water reuse.

Degradation of Agro-Industrial Wastewater Model Compound by UV-A-Fenton Process: Batch vs. Continuous Mode

The degradation of a model agro-industrial wastewater phenolic compound (caffeic acid, CA) by a UV-A-Fenton system was investigated in this work. Experiments were carried out in order to compare batch and continuous mode. Initially, batch experiments showed that UV-A-Fenton at pH 3.0 (pH of CA solution) achieved a higher generation of HO•, leading to high CA degradation (>99.5%). The influence of different operational conditions, such as H2O2 and Fe2+ concentrations, were evaluated. The results fit a pseudo first-order (PFO) kinetic model, and a high kinetic rate of CA removal was observed, with a [CA] = 5.5 × 10−4 mol/L, [H2O2] = 2.2 × 10−3 mol/L and [Fe2+] = 1.1 × 10−4 mol/L (kCA = 0.694 min−1), with an electric energy per order (EEO) of 7.23 kWh m−3 order−1. Under the same operational conditions, experiments in continuous mode were performed under different flow rates. The results showed that CA achieved a steady state with higher space-times (θ = 0.04) in comparison to dissolved organic carbon (DOC) removal (θ = 0−0.020). The results showed that by increasing the flow rate (F) from 1 to 4 mL min−1, the CA and DOC removal rate increased significantly (kCA = 0.468 min−1; kDOC = 0.00896 min−1). It is concluded that continuous modes are advantageous systems that can be adapted to wastewater treatment plants for the treatment of real agro-industrial wastewaters.