Central Wastewater Treatment Plant Research Articles

Application of an integrated dissolved ozone flotation process in centralised fracturing wastewater treatment plant

Abstract To solve the problems of unstable chemical oxygen demand (COD), turbidity and suspended solid (SS) removal for the electrocatalytic process and unstable operation of the subsequent ultrafiltration membrane–reverse osmosis membrane in a centralised fracturing wastewater treatment plant in Inner Mongolia, the integrated dissolved ozone flotation (DOF) process was proposed to replace the original electrocatalytic process. Multiple processes, such as ozonation, flotation, coagulation and decolourisation, can be achieved in one integrated DOF reactor. The results showed that the removal efficiency of COD, colour, turbidity and SS in the DOF process could reach 25.4, 49.9, 95 and 96%, respectively. Meanwhile, the treatment cost was reduced by 47% (i.e., 1.77 RMB/m3 for the DOF process) compared with the electrocatalytic process.

Case study for analyzing nutrient-management technologies at three scales within a sewershed

ABSTRACT Centralized wastewater treatment plants remove nutrients prior to discharge. Recently, technologies have become available to manage nutrients at different scales (individual buildings, neighborhoods/communities, or large centralized plants). Nutrient-recovery technologies applied upstream of the centralized treatment plant may affect both the wastewater flow rates and the nutrient fluxes reaching the plant. This study evaluates how the introduction of such upstream technologies affects the treatment efficiency and economics of nutrient management across a sewershed. Employing treatment technologies upstream from the centralized plant that receives highly loaded municipal wastewater could reduce nitrogen loading to the mainstream treatment train by over 50%, which generally reduces treatment plant effluent concentrations and saves money. In extreme cases, excessive upstream removal of nutrients can negatively affect biological treatment processes at the centralized treatment plant. Treatment of sidestreams at the centralized plant would likely be effective in reducing phosphorus loading, but not nitrogen loading, to the mainstream process.

Strategy and Master Plan for Water Supply and Domestic Wastewater in Klungkung Regency, Bali

Klungkung Regency is the second smallest regency/city area after Denpasar City. The declaration of the Indonesian government in meeting the MDG’s target for zero slums has been followed by the district government of Klungkung with a focused policy and strategic direction. The identification of slum issues is carried out on several indicators for the conditions of water supply and wastewater services. The purpose of this paper is to make long-term planning to realize integrated domestic wastewater treatment until 2033. This research uses a qualitative approach with descriptive methods and data analysis was performed by data display, verification, and conclusion drawing. To overcome the problem of fulfilling raw water, efforts are made to handle it through plans for phases I, II, III, and IV. In the period from 2019-2023, a drinking water supply system will be developed by utilizing raw water from the Muara Unda Reservoir, which is 300 L/sec. In phase III, a transmission unit will be built in the raw water delivery system from the Penida Spring with an additional capacity of 20 L/sec. In Klungkung Regency, there is no centralized wastewater treatment plant to treat wastewater from this domestic activity. Most residents in Klungkung Regency dispose of their domestic waste/water through septic tanks (for black water), while gray water is directly channeled into drainage channels or directly discharged into rivers.

Can constructed wetlands be more land efficient than centralized wastewater treatment systems? A case study based on direct and indirect land use

Compared with centralized wastewater treatment systems, constructed wetlands are generally regarded as not suitable for wide deployment due to the comparatively larger direct land area. Much of the traditional thinking is based on an onsite perspective, while the offsite information is left out. By a comparative case study with systems accounting of both onsite and offsite land use, this study questioned the traditional picture and found that constructed wetlands can be more land use efficient than centralized wastewater treatment systems. On a unit of wastewater treated basis, the land use induced by a typical constructed wetland in China is revealed to be less than half of that by the case of a centralized wastewater treatment plant or a hybrid system. On a unit removal basis for biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solid (TSS) and ammonia‑nitrogen (NH3−N), the land use induced by a constructed wetland is only around 61%, 67%, 73% and 64% of that by a centralized wastewater treatment system, respectively. Meanwhile, the indirect effect is demonstrated to be significant for these three systems: this magnitude amounts to three times the direct land occupation for a constructed wetland, and one order of magnitude higher of that for the a centralized wastewater treatment system. By a scenario analysis for China in 2017, it is preliminarily estimated that over two billion square meters of land use could be reduced if all the centralized wastewater treatment systems are replaced by constructed wetlands. The outcome may serve a benchmark and offers a new way of thinking for management of wastewater treatment systems.

The mother of corruption

A centralised wastewater treatment plant - one of the region’s largest - was to be built in Khlong Dan, Thailand, to process 525,000 m3 of wastewater daily. Staggeringly corrupt deals between politicians, public officials and businesspersons inflated land prices. Colluders were convicted following complaints by locals to the Asian Development Bank, a new prime minister and the pollution control department.

Urban wastewater as a conduit for pathogenic Gram-positive bacteria and genes encoding resistance to β-lactams and glycopeptides

The emergence and spread of clinical pathogens, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment pose a direct threat to human and animal health worldwide. In this study, we analyzed qualitatively and quantitatively urban sewage resistome for the occurrence of genes encoding resistance to β-lactams and glycopeptides in the genomes of culturable bacteria, as well as in the wastewater metagenome of the Central Wastewater Treatment Plant in Koziegłowy (Poland). Moreover, we estimated the presence of pathogenic Gram-positive bacteria in wastewater based on analysis of species-specific virulence genes in the wastewater metagenome. The results show that the final effluent contains alarm pathogens with particularly dangerous mechanisms of antibiotic resistance, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). We also noticed that during the wastewater treatment, there is an increase in the frequency of MRSA and VRE. Furthermore, the results prove the effective removal of vanA, but at the same time show that wastewater treatment increases the relative abundance of mecA and virulence genes (groES and sec), indicating the presence of clinical pathogens E. faecalis and S. aureus in the effluent released to surface waters. We also observed an increase in the relative abundance of mecA and vanA genes already in the aeration tank, which suggests accumulation of contaminants affecting enhanced selection and HGT processes in the activated sludge. Moreover, we found a relation between the taxonomic composition and the copy number of ARGs as well as the presence of pathogens at various stages of wastewater treatment. The presence of clinically relevant pathogens, ARB, including multi-resistant bacteria, and ARGs in the effluent indicates that wastewater treatment plant play a key role in the existence of pathogens and antimicrobial resistance spreading pathway in the environment and human communities, which is a direct threat to public health and environmental protection.

Commissioning of the new water line of the Central wastewater treatment plant in Prague and its impact on the operation of the existing water line.

This paper describes the commissioning of the new water line (NWL) of the Central wastewater treatment plant in Prague and also the gradual reduction of the existing water line (EWL) loading. Concerning the NWL, the gradual start-up of the process without inoculation will be described. As to the EWL, the presentation describes the adaptation of the EWL operation to the relatively quick reduction of loading to approximately 35%.

Stage by stage design for primary, conventional activated sludge, SBR and MBBR units for residential wastewater treatment and reusing

To date, there is no central wastewater (WW) treatment plant in Erbil city, Kurdistan region, Iraq. Therefore, raw WW disposes to the environment and sometimes it used directly for irrigation in some areas of Erbil city. Disposal of the untreated WW to the natural environment and using for irrigation it causes problems for the people and the environment. The aims of the current work were to study the characteristics, design of primary and different secondary treatment units and reusing of produced WW. Raw WW samples from Ashty city-Erbil city were collected and analyzed for twenty three quality parameters such as Total Suspended Solids (TSS), total dissolved solids, total volatile and non-volatile solids, total acidity, total alkalinity, total hardness, five-day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), biodegradability ratio (BOD5/COD), turbidity, etc. Results revealed that some parameters such as BOD5 and TSS were exceeded the standards for disposal of WW. Design and calculations for primary and secondary treatment (biological treatment) processes were presented. Primary treatment units such as screening, grit chamber, and flow equalization tank were designed and detailed calculation were illustrated. While, Conventional Activated Sludge (CAS), Sequencing Batch Reactor (SBR) and Moving Bed Biofilm Reactors (MBBR) were applied for the biological treatment of WW. Results revealed that MBBR was the best and economic technique for the biological treatment of WW. Treated WW is suitable for reusing and there is no restriction on use for irrigation of green areas inside Ashty city campus.

Wastewater treatment in the city of Koprivnica

Basedon the concept of sustainable development, water must be stored and protected for present and future generations. This also means saving the water through wastewater treatment. The primary role of the wastewater treatment plants is to treat wastewaters upto a satisfactory level of quality as close as possible to the natural state. The central wastewater treatment plant (WWTP) of the City of Koprivnica treats wastewater including the tertiary wastewater. Due to considerable fluctuations in wastewater volumes and loads, sequential batch reactor (SBR) technology was selected as the best solution for wastewater treatment. The final stage of treatment at the WWTP of the City of Koprivnica is the process of sludge treatment by aerobic stabilization, dehydration and MID-MIX technology, which produces a chemicallyinert powder –solidificate. Solidificate can be used in civil engineering or it can be disposed tolandfill without environmental impact. This paper analyses the physical-chemical indicators of wastewater quality (chemical oxygen demand -COD, biological oxygen demand -BOD5, total nitrogen, total phosphorus, suspended matter) on wastewater samples from the WWTP of the City of Koprivnica in a period from 2014 to 2016. The results indicate that the treatedwastewater has a satisfactory quality and that the WWTP of the City of Koprivnica works efficiently.

Comparison of life cycle toxicity assessment methods for municipal wastewater treatment with the inclusion of direct emissions of metals, PPCPs and EDCs

The occurrence of various micropollutants such as pharmaceuticals personal care products, endocrine disrupting chemicals (PPCPs/EDCs) and metals in municipal wastewater, and their poor removal efficiencies can lead to toxicity impact on humans, and freshwater and terrestrial ecosystems. Life cycle assessment is an efficient and effective tool to evaluate the environmental impact of wastewater treatment plants, but guidelines for toxicity assessment are lacking due to the complexity. This study aims to evaluate both life cycle inventory by including metals and PEC, and life cycle toxicity assessment (LCIA) methods namely CML-IA, Recipe, USEtox, EDIP 2003 and IMPACT 2002+ in midpoint category with a large centralised wastewater treatment plant in Malaysia as a case study. The removal efficiencies of metals and PPCPs/EDCs in the wastewater ranged from 9% to 99% and no clear patterns were found about occurrence and removal efficiencies of metals and PPCPs/EDCs in developing and developed countries. The inclusion of metals and PPCPs/EDCs in effluent resulted in 76% increase in freshwater ecotoxicity potential (FEP) and 88% increase in terrestrial ecotoxicity potential (TEP) while only 4% increase in human toxicity potential (HTP). The results indicate the importance of including direct emissions such as metals and PPCPs/EDCs even in low-strength municipal wastewater for environmental toxicity assessment. The comparison of five LCIA methods suggests that HTP assessment is more challenging due to inconsistency between five LCIA methods while CML-IA, Recipe, and IMPACT 2002+ achieved consistent human toxicity and ecotoxicity assessment results in the WWTP. The results highlight the importance of sampling and inclusion of metals and PPCPs/EDCs data especially prioritised micropollutants for life cycle toxicity assessment and recommends LCIA methods for ecotoxicity assessment of WWTPs in the current scientific development situation on toxicity studies, which can provide guidance to researchers for life cycle toxicity assessment of wastewater treatment.

Occurrence, distribution, and risk assessment of pharmerciuticals in wastewater and open surface drains of peri-urban areas: Case study of Juja town, Kenya

The occurrence of Active Pharmaceutical Ingredients (APIs) in the environment is becoming a major area of concern due to their undesirable effects on non-target organisms. This study investigated the occurrence and risk of contamination by five antibiotics and three antiretrovirals drugs in a fast-growing peri-urban area in Kenya, with inadequate sewer system coverage. Due to poor sewage connectivity and poorly designed decentralized systems, wastewater is directly released in open drains. Water and sediment samples were collected from open surface water drains, while wastewater samples were collected from centralized wastewater treatment plants (WWTP). Solid-phase extraction and ultrasonic-assisted extraction for the aqueous and sediment samples respectively were carried out and extracts analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) using isotopically labeled internal standards. APIs were observed with the detection frequency ranging from 36% to 100%. High mean concentrations of 48.7 μg L−1, 108 μg L−1, and 532 μg L−1 were observed in surface drains for Lamivudine (3 TC), Sulfamethoxazole (SMX), Ciprofloxacin (CIP) respectively. Drain sediments also showed high concentrations of APIs ranging from 2.1 to 13,100 μg kg−1. APIs in this study exceeded those observed in existing literature studies. JKUAT WWTP removal efficiencies varied from −90.68% to 72.67%. Total APIs emission load of the study area was 3550 mg d−1 with WWTP effluent contributing higher loads (2620 mg d−1) than surface water drains (640 mg d−1). Zidovudine (ZDV), nevirapine (NVP), and trimethoprim (TMP) loads in drains, however, exceeded WWTP effluent. Low to high ecotoxicity risk of the individual APIs were observed to the aquatic environment, with high risks for the development of antibiotic resistance in microbiome as determined by the risk quotient (RQ) approach. Risk management through efficient wastewater collection, conveyance, and treatment is necessary to suppress the measured concentrations.

Upgrading a large and centralised municipal wastewater treatment plant with sequencing batch reactor technology for integrated nutrient removal and phosphorus recovery: Environmental and economic life cycle performance

Although nutrient removal and recovery from municipal wastewater are desirable to protect phosphorus resource and water-bodies from eutrophication, it is unclear how much environmental and economic benefits and burdens it might cause. This study evaluated the environmental and economic life cycle performance of three different upgraded Processes A, B and C with commercially available technologies for nutrient removal and phosphorus recovery based on an existing Malaysian wastewater treatment plant with a sequencing batch reactor technology and diluted municipal wastewater. It is found that the integration of nutrient removal, phosphorus recovery and electricity generation in all upgraded processes reduced eutrophication potential by 62–76%, and global warming potential by 7–22%, which, however, were gained at the cost of increases in human toxicity, acidification, abiotic depletion (fossil fuel) and freshwater ecotoxicity potentials by an average of 23%. New technologies for nutrient removal and phosphorus recovery are thus needed to achieve holistic rather than some environmental benefits at the expense of others. In addition, the study on two different functional units (FU), i.e. per m3 treated wastewater and per kg struvite recovered, shows that FU affected environmental assessment results, but the upgraded Process C had the least overall environmental burden with either of FUs, suggesting the necessity to use different functional units when comparing and selecting different technologies with two functions such as wastewater treatment and struvite production to confirm the best process configuration. The total life cycle costs of Processes A, B and C were 10.7%, 29.8% and 28.1%, respectively, higher than the existing process due to increased capital and operating costs. Therefore, a trade-off between environmental benefits and cost has to be balanced for technology selection or new integrated technologies have to be developed to achieve environmentally sustainable wastewater treatment economically.

Penataan Rancangan Lokasi Instalasi Pengolahan Air Limbah Terpadu Kampus Institut Pertanian Bogor

Until now there has not been a centralized Wastewater Treatment Plant (WWTP) in IPB, even though there are wastewater treatments in several locations that are scattered in the campus area. Various activities on the Dramaga IPB campus have the potential to produce wastewater, such as laboratory activities, especially chemical and biological laboratories, canteens, offices, and dormitories. The existence of scattered laboratories requires a centralized and integrated WWTP. For this reason, mapping of wastewater distribution is needed to arrange the location of the wastewater treatment plant, within the campus. Interviews with the perpetrators of activities, measurement of wastewater quality, and sampling, were carried out at the work units producing wastewater on the campus of IPB. The distribution of wastewater was grouped according to the location of the work units producing waste and identified the types of waste produced (B3-dangerous and toxic and non-B3), then presented in a map. The map was used as a reference in determining the location of wastewater treatment plants. The results showed that each work unit contributes organic waste that was not too different, the source of inorganic and B3 wastewater distribution followed the location of the laboratory which was also quite scattered in the Dramaga IPB campus area. Based on the distribution of available waste, the presence of wastewater in the campus environment of IPB was divided into two regional groups. Therefore, the location of the wastewater treatment plant was directed at two locations, namely on the Northeast side (IPAL I) and the West side (IPAL II) of IPB campus.
 
 Keywords: wastewater characteristics, wastewater distribution, wastewater treatment plant

The statistical and technical evaluation of the wastewater treatment plants in holiday resorts

The aim of this study is technical and statistical evaluation of wastewater treatment plants existing at the holiday resorts in areas surrounding Izmir City. The study was carried out in the time period from August to September 2018. Within the scope of the study, 150 holiday resorts were investigated and listed. The necessary permissions were obtained and the treatment plants were visited at their current locations. Most of the wastewater treatment plants are embedded in the ground and are referred to as package treatment systems. They are used at holiday resorts for many reasons, such as smell and noise control. Many parameters have been considered within the scope of the study, such as installed power of the plant, influent wastewater flow and pollutant concentration, the properties of the sludge, sludge disposal methods, effluent wastewater parameters, the method and location of effluent water discharge, operation period of the wastewater treatment plant. As a result of this study, it has been found that the low cost package treatment systems were generally preferred. The systems that required most energy were the blowers. In order to provide clean and smooth environment, the use of central wastewater treatment plants is more suitable than the use of package treatment systems

Wastewater treatment system optimization with an industrial symbiosis model: A case study of a Chinese eco‐industrial park

AbstractIn Chinese industrial parks, the centralized wastewater treatment plant (CWWTP) is an essential shared infrastructure to further purify the in‐plant pretreated industrial wastewater. Most of the contaminants, such as organic matter, are removed by in‐plant wastewater treatment to guarantee the safety and efficiency of the CWWTP. Carbon source shortages are common in the denitrification process in CWWTPs, and such issues are generally solved by adding external carbon sources, such as glucose. Some biodegradable organics that are abundant in industrial wastewater, such as food production wastewater, can be utilized as the external carbon sources for denitrification. This study proposed an industrial symbiosis‐based model to optimize the wastewater treatment system in industrial parks by reusing organic matter in food wastewaters as the external carbon source for advanced treatment processes in CWWTPs. A case study of a Chinese eco‐industrial park is investigated to verify the technical and economic feasibility of the model. The case study indicates that the overall cost‐savings potential of the model is approximately 6.55 million Chinese Yuan (CNY) per year, accounting for approximately 20% of the annual operating cost of the CWWTP. Additionally, the mitigation potential of greenhouse gas (GHG) emissions is 5977 t CO2‐eq per year, accounting for 1.7% of the GHG emissions of the original model. Furthermore, potential barriers to implementing the IS model and the relevant policy implications are discussed.

Application of constructed wetland for advanced treatment of industrial wastewater

An experimental study to use a pilot vegetated submerged bed (VSB) wetland for the advanced treatment of effluent from the central wastewater treatment plant (CWWTP) of an industrial zone was carried out. The pilot VSB wetland included reeds (Phragmites australis), cattail (Typha orientalis), and blank cells in parallel. The constructed wetland was observed to be a suitable measure for wastewater reuse via the high performance of organic matter, turbidity removal, and detoxification. At loading rates of up to 250 kg chemical oxygen demand (COD) ha-1d-1, both cells with emergent plants obtained high efficiency of contaminant removal. Suspended solids (SS) and turbidity removal reached 67-86% and 69-82%, respectively. The COD removal efficiencies of the reed and cattail cells at a loading rate of 130 kg COD ha-1d-1were 47 and 55%, respectively. At a high loading of 400 kg COD ha-1d-1, the toxicity unit (TU) reduced from 32-42 to 4.9 and 4.2 in the effluent of the cattail and reed cells, respectively. Especially at loadings of 70, 130, and 185 kg COD ha-1d-1, the effluent TU was less than 3.0, corresponding to a non-toxic level to the ecosystem. The effluent quality met industrial or landscaped wastewater reuse at these loading rates.

Emerging concerns of VOCs and SVOCs in coking wastewater treatment processes: Distribution profile, emission characteristics, and health risk assessment

In this study, the distribution profiles, emission characteristics, and health risks associated with 43 volatile and semi-volatile organic compounds, including 15 phenols, 18 polycyclic aromatic hydrocarbons (PAHs), 6 BTEX, and 4 other compounds, were determined in the wastewater treatment plant (WWTP) of a coking factory (plant C) and the succeeding final WWTP (central WWTP). Total phenols with a concentration of 361,000 μg L−1 were the predominant compounds in the influent wastewater of plant C, whereas PAHs were the major compounds in the final effluents of both coking WWTPs (84.4 μg L−1 and 30.7 μg L−1, respectively). The biological treatment process in plant C removed the majority of volatile organic pollutants (94.1%–99.9%). A mass balance analysis for plant C showed that biodegradation was the main removal pathway for all the target compounds (56.6%–99.9%) except BTEX, chlorinated phenols, and high molecular weight (MW) PAHs. Chlorinated phenols and high MW PAHs were mainly removed via sorption to activated sludge (51.8%–73.2% and 60.2%–75.9%, respectively). Air stripping and volatilization were the dominant mechanisms for removing the BTEX compounds (59.8%–73.8%). The total emission rates of the detected volatile pollutants from plant C and the central WWTP were 1,640 g d−1 and 784 g d−1, respectively. Benzene from the equalization basins of plant C and the central WWTP corresponded to the highest inhalation carcinogenic risks (1.4 × 10−3 and 3.2 × 10−4, respectively), which exceeded the acceptable level for human health (1 × 10−6) recommended by the United States Environmental Protection Agency. The results showed that BaP exhibited the highest inhalation non-cancer risk, with a hazard index ratio of 70 and 30 for plant C and the central WWTP, respectively. Moreover, the excess sludge generated during wastewater treatment should also be carefully handled because it adsorbed abundant PAHs and chlorinated phenols at coking plant C (58,000 μg g−1 and 3,500 μg g−1) and the central WWTP (622 μg g−1 and 54 μg g−1).

Removal of pharmaceuticals from nitrified urine by adsorption on granular activated carbon

Nitrification and distillation of urine allow for the recovery of all nutrients in a highly concentrated fertilizer solution. However, pharmaceuticals excreted with urine are only partially removed during these two process steps. For a sustainable and safe application, more extensive removal of pharmaceuticals is necessary. To enhance the pharmaceutical removal, which is already occurring during urine storage, nitrification and distillation, an adsorption column with granular activated carbon (GAC) can be included in the treatment train. We executed a pilot-scale study to investigate the adsorption of eleven indicator pharmaceuticals on GAC. During 74 days, we treated roughly 1000 L of pre-filtered and nitrified urine spiked with pharmaceuticals in two flow-through GAC columns filled with different grain sizes. We compared the performance of these columns by calculating the number of treated bed volumes until breakthrough and carbon usage rates. The eleven spiked pharmaceuticals were candesartan, carbamazepine, clarithromycin, diclofenac, emtricitabine, hydrochlorothiazide, irbesartan, metoprolol, N4-acetylsulfamethoxazole, sulfamethoxazole and trimethoprim. At the shortest empty bed contact time (EBCT) of 25 min, immediate breakthrough was observed in both columns shortly after the start of the experiments. Strong competition by natural organic material (NOM) could have caused the low pharmaceutical removal at the EBCT of 25 min. At EBCTs of 70, 92 and 115 min, more than 660 bed volumes could be treated until breakthrough in the column with fine GAC. The earliest breakthrough was observed for candesartan and clarithromycin. On coarse GAC, only half the number of bed volumes could be treated until breakthrough compared to fine GAC. The probable reason for the later breakthrough with fine GAC is the smaller intraparticle diffusive path length. DOC and UV absorbance measurements at 265 nm indicated that both parameters can be used as indicators for the breakthrough of pharmaceuticals. In contrast to pharmaceuticals and DOC, the nutrient compounds ammonium, nitrate, phosphate, potassium and sulfate were not removed significantly. A comparison with literature values suggests that the amount of GAC needed to remove pharmaceuticals from human excreta could be reduced by nearly two orders of magnitude, if urine were treated on site instead of being discharged and treated in a centralized wastewater treatment plant.

Can wastewater feed cities? Determining the feasibility and environmental burdens of struvite recovery and reuse for urban regions

Phosphorus (P) resources are decreasing at an alarming rate due to global fertilizer use and insufficient nutrient recovery strategies. Currently, more circular approaches are promoted, such as recovering P from wastewater in the form of struvite. This is especially attractive for urban areas, where there is a growing trend of local crop production and large volumes of wastewater are treated in centralized wastewater treatment plants (WWTPs). This research aims to assess the technical and environmental feasibility of applying a struvite recovery and reuse strategy to meet the P requirements to fertilize the agricultural fields of an urban region. To do so, we analyze the potential P recovery and the environmental impacts of integrating three recovery technologies (REM-NUT®, Ostara® and AirPrex®) in the two biggest WWTPs of the Àrea Metropolitana de Barcelona. The results show that all technologies are able to recover between 5 and 30 times the amount of P required to fertilize the agricultural area of the region annually (36.5 t). As can be expected, including P recovery technologies result in additional impacts per m3 of wastewater due to increased electricity consumption and chemicals required for the struvite precipitation. However, struvite recovery results in less eutrophication potential, especially in the REM-NUT® case, with an average reduction of 5.4 times. On the other hand, Ostara®, that recovers P from the digestate, had the lowest impacts (9 kgCO2eq/kgP), even compared to the production of mineral fertilizer. When we apply our findings to the whole region, we can see that chemical use for struvite precipitation and energy consumption during the wastewater treatment process are the elements with the greatest impact. Thus, choosing the most appropriate technology in the most suitable WWTP is the most efficient strategy to diminish the environmental impacts of the system.

Eco‐efficiency of water and wastewater management in food production: A case study from a large dairy in Denmark

AbstractRising water demands and pressures on water resources call for water management in industrial production. An eco‐efficiency framework may provide justification for water consumption and treatment by combining environmental and economic dimensions in a life cycle perspective. We used principles of value added and value chain assessment (VCA) in the life‐cycle system boundaries for a consistent assessment of eco‐efficiency. The method was demonstrated for a membrane bioreactor‐based, decentralized wastewater treatment and reuse in a dairy. The LCA results showed that decentralized wastewater treatment and reuse in the dairy will improve the aquatic environment by 80% (freshwater) and 51% (marine water), but increase the negative impact on climate change by 27% compared to conventional wastewater treatment. The VCA revealed that the decentralized alternatives would increase the value added by 1.3–1.4 €/m3 wastewater in the dairy, but also incur a value loss of 1.4–1.9 €/m3 for associated stakeholders such as the centralized wastewater treatment plant. The case study revealed the critical nature of a well‐defined system boundary that includes impacts along the entire value chain and exposed pros and cons for decision‐makers at both the system level and individual stakeholder level.