Global warming and the greenhouse effect are two of the most important environmental problems. Carbon dioxide, methane, and nitrous oxide emissions are the main greenhouse gas emissions in wastewater treatment plants. In this study, the greenhouse gas emission sources in a wastewater treatment plant were determined. Direct (from fossil fuel combustion, methane emissions, and process emissions of the other greenhouse gases) and indirect emissions (primarily from electricity use) in the plant were monitored. The optimum influent characteristics and operating conditions have been defined by using Monte Carlo simulation to minimize the emissions. The results revealed that the highest direct greenhouse gas emission was observed in August with the value of 23.328 kg CO2‐eq d–1 and the lowest emission was 7.56 kg CO2‐eq d–1 measured in January. The aeration tank is a major source of greenhouse gas emissions. Indirect emission has occurred because of the anaerobic digester but the biogas has been cogenerated in the plant, so it has been ignored for the calculation. According to the simulation study, if the plant is operated under optimum operating conditions, it can emit the lowest amount of greenhouse gas emissions. The optimum removal values required for the minimum greenhouse gas emissions are 79% for chemical oxygen demand, 75% for biochemical oxygen demand, and 82% for total suspended solid. The optimum operating conditions for the aeration tank, which is the major source of emission, are 5.33 h of hydraulic retention time, 0.215 d of solid retention time, and 0.999 for food/microorganisms. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Available fresh water demand of a growing population is a fundamental concern of water resource sustainability. Dairy industry wastewater treatment plants have been considered a major polluter due to the high organic content and large wastewater discharges. Grey water footprint (GWF) was developed by the Water Footprint Network (WFN) as a measure of the water pollution loading. In this study, four treatment scenarios including no treatment process (Scenario-1), primary treatment using Dissolved Air Flotation (DAF) (Scenario-2), secondary treatment using DAF and a Upflow Sludge Bed (UASB) reactor (Scenario-3), and a DAF and UASB with a reuse application applying reverse osmosis (RO) (Scenario-4) have been studied for a full-scale dairy industry wastewater treatment plant. For these four scenarios, GWF assessment was undertaken using the WFN method by taking into consideration three pollutant parameters, chemical oxygen demand (COD), fats, oil and grease (FOG) and total suspended solids (TSS). The results show that the GWF of Scenario-4 for COD was lowest with the value of −5,609 m3/d and Scenario-1 has the highest GWF for TSS with the value of 41,026 m3/d. According to the assessment results, reuse applications decrease the GWF values.

In this paper, (CO2) and methane (CH4) emissions of an industrial wastewater treatment plant were monitored. GHG emissions originated from treatment processes were considered as the direct emissions and determined using closed chamber method. GHG emission due to energy consumption was regarded as the indirect emissions. In the second stage of the study, it was aimed to reduce GHG emissions in terms of water–energy nexus. If the plant is operated under design conditions, energy consumption would be lower according to water–energy nexus. Also, the effect of design conditions on GHG emissions was investigated. Firstly, the correlation was defined between GHG emissions and operational parameters in terms of chemical oxygen demand (COD) and wastewater flow rate using Monte Carlo simulation. Then, design COD and wastewater flow rate were simulated to determine the possible GHG emission for each month. The simulation results show that minimization of GHG emissions might be possible if wastewater plant is operated under design conditions. The minimum greenhouse gas emission in the result of the simulation study is 8.25 kg CO2-eq/d if the plant is operated under design COD and flow rate. Total reduction in GHG emissions is approximately 30% if the plant is operated under design conditions.

Paint manufacturing process has several unfavorable aspects to the environment in Turkey. One of these impacts is wastewater treatment. Paint wastewater contains huge amounts of toxic chemical substances, bio refractory compounds, pigments and microorganisms. So, advanced treatment requirement is available to dispose of colour, microorganisms and chemical oxygen demand (COD). The high organic content of wastewater causes serious environmental challenges and contamination for the living organisms and the ecosystem in the receiver media unless it is treated adequately. In this context, the treatment process to be implemented should be preferred in such a way as to give the least damage to the environment. In this study, three treatment scenarios that contain electrocoagulation (Scenario-1), Fenton process (Scenario-2) and membrane distillation (Scenario-3) have been created for wastewater treatment facility of a paint industry in Turkey. For three scenarios, environmental impact assessment has been carried out with Fine-Kinney method. It is aimed to choose best environmental technology before investment. The evaluation results revealed that Scenario-2 has the less environmental impacts that total impact value is 556. Scenario-1 has the highest total impact value as 756, relatively. Total impact value related to Scenario-3 is 637. According to the evaluation results, Fenton process is the best environmental-friendly treatment technology for wastewater treatment of a paint industry in Turkey.