Wastewater Management Technologies Research Articles

Spatiotemporal pattern of greenhouse gas emissions in China’s wastewater sector and pathways towards carbon neutrality

Greenhouse gas (GHG) emissions from the wastewater sector are a major contributor to the overall GHG emissions of all countries, however, there is currently a lack of global, national-scale, detailed spatiotemporal emission data. In this study we elaborated dynamic plant-resolved emission factor values based on the case-specific operating parameters of each municipal wastewater treatment plant (WWTP) and the associated sewers and sludge disposal utilities in China, contrasting with previous estimations that typically focused on WWTP operation without differentiating their spatiotemporal discrepancies. We demonstrate here that China’s municipal wastewater industry generated 53.0 MtCO2e in total GHG emissions in 2019, with the northern and southern areas exhibiting noticeably higher GHG intensities. Due to improved wastewater treatment, the national average wastewater GHG intensity grew by 17.2% between 2009 and 2019, although it is anticipated that the intensity will begin to fall starting in 2020 at rates dependent on the chosen treatment methods. A net-zero emission by the entire sector may be achieved as early as 2044 with continually increasing decarbonized energy and a progressive shift to resource-oriented operations, compared with just a 23.7% decrease by 2050 under the baseline scenario. Joint efforts at the scientific, economic and policy level will be required to make this happen. This study may serve as a roadmap for developing carbon-neutral wastewater management policies and technologies in China and the rest of the globe. Based on case-specific operating parameters of each municipal wastewater treatment plant and the associated sewers and sludge disposal utilities, this study presents a detailed analysis of the current carbon footprint of the wastewater sector in China and scenarios for reducing future emissions.

Domestic wastewater reduction using constructed wetlands

Domestic wastewater is household liquid waste that comes from sinks, bathrooms, and wastewater from washing machines. In Johan Pahlawan Sub-district, West Aceh District, the community and government's concern is still low towards achieving environmental health where the coverage of wastewater management has not been optimized. This is shown by people who do not manage wastewater properly. One of the alternative domestic wastewater management technologies is the concept of constructed wetlands with phytoremediation techniques. This study aims to determine the efficiency of reducing wastewater concentrations using phytoremediation with Eichhornia Crassipes plants, Pandanus amaryllifolius plants and Scirpus grossus plants. After the phytoremediation process with the concept of CWs-SF and CWs-SSF, it shows that the use of pandanus has not been effective in reducing contaminant levels in domestic wastewater. While Eichhornia Crassipes and Scirpus grossus plants are much better at reducing wastewater concentrations. The efficiency of reducing BOD values with a contact time of 3 to 9 days can reduce BOD levels by 80%-91%, COD and TSS can reduce the wastewater to 89%-90%, the temperature of the wastewater has been qualified with Eichhornia Crassipes and wlingen plants with 290C, and the pH of the wastewater has increased to 7.5-8.

A Review on the Production Methods and Applications of Graphene-Based Materials.

Graphene-based materials in the form of fibres, fabrics, films, and composite materials are the most widely investigated research domains because of their remarkable physicochemical and thermomechanical properties. In this era of scientific advancement, graphene has built the foundation of a new horizon of possibilities and received tremendous research focus in several application areas such as aerospace, energy, transportation, healthcare, agriculture, wastewater management, and wearable technology. Although graphene has been found to provide exceptional results in every application field, a massive proportion of research is still underway to configure required parameters to ensure the best possible outcomes from graphene-based materials. Until now, several review articles have been published to summarise the excellence of graphene and its derivatives, which focused mainly on a single application area of graphene. However, no single review is found to comprehensively study most used fabrication processes of graphene-based materials including their diversified and potential application areas. To address this genuine gap and ensure wider support for the upcoming research and investigations of this excellent material, this review aims to provide a snapshot of most used fabrication methods of graphene-based materials in the form of pure and composite fibres, graphene-based composite materials conjugated with polymers, and fibres. This study also provides a clear perspective of large-scale production feasibility and application areas of graphene-based materials in all forms.

A Systematic Review of Drivers of Sustainable Wastewater Treatment Technology Adoption

In this systematic review we explore the forces that encourage or hinder the adoption of wastewater treatment and/or management technology. Our literature search uncovered 37 sources that discuss these issues. Retrieved sources were then subjected to qualitative synthesis. We adopted a systems-theory perspective in analyzing the qualitative data and provide insights into the interaction between the political environment and societal and organizational systems. Our findings indicate that sustainable change can best be achieved through understanding the interaction between systems and their actual capability to meet the needs of related systems. Societal-level systems emerge as having the possibility to influence the political environment as well as organizations.

Temperature analysis of a novel MAIB reactor during the treatment of wastewater from recycled paper mill

Abstract Anaerobic digestion (AD) is an essential technology for wastewater management, resource recovery and biogas production, and it is considered as an efficient and reliable treatment method for many wastewaters. Operating parameters have been shown to directly affect the stability and treatment performance of AD, especially temperature. For 180 days, the AD of recycled paper mill wastewater (RPMW) was carried out in a modified anaerobic inclining-baffled (MAIB) reactor under various temperature conditions, i.e. 29 °C (low mesophilic), 37 °C (mesophilic) and 55 °C (thermophilic). It was found that total COD removal of 94, 96 and 76%, and methane yields of 0.125, 0.196 and 0.256 L CH4/g CODremoved were attained at temperatures of 29, 37 and 55 °C, respectively. Throughout the three transition periods, the pH level in the MAIB reactor fluctuated slightly within the range of 5.8–6.5 without affecting the system stability. The results concluded that thermophilic condition strongly influenced the MAIB reactor performance, leading to lower COD removal, higher methane yield and gradually recovered pH level.

Removal of biological effects of organic pollutants in municipal wastewater by a novel advanced oxidation system

The Advanced Oxidation System (AOS) is a novel electrochemical advanced oxidation process that effectively removes bacterial and organic contaminants from wastewater. However, potential formation of secondary oxidative species may pose additional hazards to aquatic organisms living in the receiving water affected by the post-treatment effluent. The effect of exposure to AOS treated water, especially the potential long-term effects on aquatic organisms, requires further investigation to demonstrate both efficacy and safety of this process. To examine the potential adverse effects of AOS treated water, three aquatic species, including daphnia, zebrafish, and rainbow trout, were exposed to treated and untreated municipal wastewater effluent (MWE) spiked with one of two model organic contaminants, benzo[a]pyrene (BaP) and 17β-estradiol (E2). The results indicated AOS treatment significantly reduced the adverse effects caused by exposure to MWE and model organic contaminants to baseline levels in daphnia (reduced fecundity), zebrafish embryo (elevated EROD activity), and rainbow trout (elevated plasma vitellogenin). The Ames test was also conducted to confirm the removal efficacy of carcinogenicity of BaP spiked in MWE. Overall, this study demonstrated that AOS treatment is a promising and environmentally friendly technology for wastewater treatment, remediation, and management.

Study of free nitrous acid (FNA)-based elimination of sulfamethoxazole: Kinetics, transformation pathways, and toxicity assessment

Free nitrous acid (FNA)-based applications have been broadly adopted in the development of novel wastewater management technologies, but a basic understanding of the effect of the chemical properties of FNA on the elimination of micropollutants is still lacking. This study aims to comprehensively evaluate FNA-based elimination of sulfamethoxazole (SMX), which is a typical species of sulphonamide antibiotics. Batch experiments were conducted under different influencing factors to investigate the antibiotics elimination processes. We found that FNA showed specific efficacy on sulphonamides characterized by sulfonamide and aniline functional groups, such as SMX. SMX degradation was affected by the initial SMX concentration, FNA concentration and solution pH and described by d[SMX]/dt=−0.29e−1.69pH[SMX]0.945[FNA]1.35. The cationic forms of SMX were more reactive towards FNA-based active components. Sulfonamide bond (S-N or C-S bonds) cleavage, nitrosubstitution, deamination and radical oxidation were proposed to be the relevant transformation pathways. The FNA-based technique was not effective for diminishing toxicity, but this process could strongly control antibacterial activity.

Syntrophic acetate oxidation replaces acetoclastic methanogenesis during thermophilic digestion of biowaste

BackgroundAnaerobic digestion (AD) is a globally important technology for effective waste and wastewater management. In AD, microorganisms interact in a complex food web for the production of biogas. Here, acetoclastic methanogens and syntrophic acetate-oxidizing bacteria (SAOB) compete for acetate, a major intermediate in the mineralization of organic matter. Although evidence is emerging that syntrophic acetate oxidation is an important pathway for methane production, knowledge about the SAOB is still very limited.ResultsA metabolic reconstruction of metagenome-assembled genomes (MAGs) from a thermophilic solid state biowaste digester covered the basic functions of the biogas microbial community. Firmicutes was the most abundant phylum in the metagenome (53%) harboring species that take place in various functions ranging from the hydrolysis of polymers to syntrophic acetate oxidation. The Wood-Ljungdahl pathway for syntrophic acetate oxidation and corresponding genes for energy conservation were identified in a Dethiobacteraceae MAG that is phylogenetically related to known SAOB. 16S rRNA gene amplicon sequencing and enrichment cultivation consistently identified the uncultured Dethiobacteraceae together with Syntrophaceticus, Tepidanaerobacter, and unclassified Clostridia as members of a potential acetate-oxidizing core community in nine full-scare digesters, whereas acetoclastic methanogens were barely detected.ConclusionsResults presented here provide new insights into a remarkable anaerobic digestion ecosystem where acetate catabolism is mainly realized by Bacteria. Metagenomics and enrichment cultivation revealed a core community of diverse and novel uncultured acetate-oxidizing bacteria and point to a particular niche for them in dry fermentation of biowaste. Their genomic repertoire suggests metabolic plasticity besides the potential for syntrophic acetate oxidation.1dV765cjiwNJNY-1M7VNFLVideo

Enhanced solar evaporation using a photo-thermal umbrella for wastewater management

Zero-liquid discharge is an emerging wastewater management strategy that maximizes water recovery for reuse and produces a solid waste, thereby lowering the environmental impact of wastewater disposal. Evaporation ponds harvest solar energy as heat for zero-liquid discharge, but require large land areas due to low evaporation rates. Here, we demonstrate a passive and non-contact approach to enhance evaporation by more than 100% using a photo-thermal device that converts sunlight into mid-infrared radiation where water is strongly absorbing. As a result, heat is localized at the water’s surface through radiative coupling, resulting in better utilization of solar energy with a conversion efficiency of 43%. The non-contact nature of the device makes it uniquely suited to treat a wide range of wastewater without contamination, and the use of commercial materials enables a potentially low-cost and highly scalable technology for sustainable wastewater management, with the added benefit of salt recovery. By passively evaporating water from waste streams, evaporation ponds work with different waste streams but need large areas due to low evaporation rates. This study shows that a photo-thermal device converting sunlight into mid-infrared radiation could enhance evaporation and reduce land needs.

Cavitation as a Potential Technology for Wastewater Management – An Example of Enhanced Nutrient Release from Secondary Pulp and Paper Mill Sludge

Wastewater recycling and sludge removal in the paper industry account for about 60 % of all process costs. New and environmentally friendly wastewater treatment techniques are, therefore, continually being developed. Cavitation exploitation is currently a well-investigated topic that is also interesting for the paper production industry. This study investigates efficiency of hydrodynamic cavitation alone and in combination with the addition of NaOH for the treatment of secondary pulp and paper mill sludge in order to enhance nutrient release. First, two laboratory-scale devices were tested: the blow-through and the rotating hydrodynamic cavitation generator. The latter set-up proved to be more efficient: therefore, further experiments were performed on its pilot-scale version. The results showed an increase of soluble chemical oxygen demand (CODs) by 514 mg/L, total nitrogen (Nt) by 17.4 mg/L, and total phosphorous (Pt) by 2.3 mg/L. To further increase nutrient release combination of cavitation and sludge sample alkalinization was tested. The addition of NaOH and 30 min cavitation of secondary sludge (500 L) significantly improved CODs and Nt release by 2400 mg/L and 120 mg/L, respectively. Microbiological photos revealed a definite disintegration of sludge flocks. According to our estimates, 1.9 kg of released CODs from alkaline pre-treated and cavitated sludge would cost only one euro.

Activation of fulvic acid-like in paper mill effluents using H2O2/TiO2 catalytic oxidation: Characterization and salt stress bioassays.

Increasing environmental concerns about organic waste in paper mill effluents demand alternative wastewater management technology. We reported novel activation of fulvic acid-like in paper mill effluents using hydrogen peroxide (H2O2) as oxidizer and titanium oxide (TiO2) as catalyst. Spectroscopic characteristics of fulvic acid-like in paper mill effluents before and after activation (PFA and PFA-Os, respectively) were compared with a benchmark fulvic acid extracted from leonardite (LFA). Results indicated that PFA-Os exhibited less lignin structures, more functional groups and lower molecular weight than PFA, sharing much similarity with LFA. Among PFA-Os with varying degrees of oxidation, PFA-O-3 activated with 1:2 vol ratio of paper mill effluent and 30% H2O2 for 20 min digestion at 90 °C stands out to be the optimal for further examination of its biological activity. Bioassays with rice seed/seedling indicated that applications of LFA at 2-5 mg-C/L and PFA-O-3 at 60-100 mg-C/L significantly increased rice seed germination rate and seedling growth under salt stress imposed with 100 mM NaCl. The mechanism was mainly through reduced oxidative damage via activation of antioxidative enzymes and lipid peroxidation. This study provides the needed technical basis of safer and cleaner technologies for innovative management of paper mill effluents.

Sustainable wastewater management technology for tourism in Thailand: case and experimental studies.

Thailand has adopted the concept of eco-tourism as a protocol to protect environmental resources. One of the key factors in enabling the achievement of this goal is the improvement of the quality of effluent from those homestays and resorts which still lack efficient on-site wastewater treatment. This research utilized case studies of subsurface flow constructed wetlands (SFCWs), planted mainly with the Indian shot (Canna indica L.), which were designed to treat wastewaters at three resorts located in Amphawa District, Samut Songkram Province in central Thailand. The results showed that the treated effluent was of sufficient quality to meet the building effluent standards Type C, which require the concentrations of biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN) and suspended solids (SS) to be less than 40, 40 and 50 mg/L, respectively. In addition, the first-order kinetic constants for the design and operation of SFCWs were determined. For treating wastewater containing organic substances, with no prior pre-treatment, the first-order kinetic constant of 0.24 1/d can be applied to predict effluent quality. For treating other types of domestic wastewater, a first-order kinetic constant in the range 0.40-0.45 1/d can be used when sizing and operating SFCWs. This research highlights the great potential of SFCWs as a sustainable wastewater management technology.

Microalgae–bacteria consortium treatment technology for municipal wastewater management

The discharge of inadequately treated municipal wastewater in the developing countries is the major cause of environmental pollution in urban areas. However, the effort was made to minimize this burden using conventional wastewater treatment methods that require high capital and operational costs and are not affordable. Researchers are still looking for the cost-effective, efficient and environmentally compatible wastewater treatment technologies. Hence, this study aimed to investigate the potential of native microalgae–bacteria consortia for the removal of nutrient and organic pollutants from primary-treated municipal wastewater. Microalgae–bacteria treatment system was established by combining pre-cultured native algae consortia dominated by Chlorella sp., Chlamydomonas sp. and Scenedesmus sp. of the class Chlorophyceae with naturally existing municipal wastewater bacteria. Microalgae–bacteria culture acclimatization was performed and the actual experiment was carried out at 18% culture to wastewater by volume in photobioreactor at a light intensity of 120 μE/m2s. The maximum removal of TKN 69%, TP 59%, PO43−_ P 73%, COD 84% and BOD5 85% was observed in the combined treatment system, whereas for bacteria stand-alone treatment system, the maximum removal of TKN 31%, TP 56%, PO43−_ P 50%, COD 44% and BOD5 52% was recorded. Statistically significant differences were observed for the removal of NH3–N, TKN and PO43−_ P at p < 0.05 but statistically insignificant differences were observed for TP, COD and BOD5 in the combined treatment system. The study results suggest that the native microalgae consortia identified in the local environment can effectively reduce organic and nutrient pollutants from the primary-treated municipal wastewater. Generally, the performance evaluation of combined microalgae–bacteria treatment technology was efficient in municipal wastewater management and promising to scale up at industrial level.

Community engagement and pollution mitigation at Kandy Lake, Sri Lanka

Abstract Kandy City is a UNESCO world heritage site. Being the second largest city in Sri Lanka and host to the annual Esala Perahara festival, it has a floating population two to three times its 120,000 permanent residents. Among the city's key landmarks is Kandy Lake, a culturally, environmentally, and economically significant ornamental lake. Nevertheless, inadequate urban development regulation has resulted in serious pollution of the lake. An integrated remedial measure was needed to improve the urban lake's water quality sustainably, for the Kandy community and their cultural heritage. A project was initiated by the University of Peradeniya (UOP), Sri Lanka, and the Nanyang Environment and Water Research Institute (NEWRI), Singapore. It started with modelling of Kandy Lake and community surveys, demonstrated implementation of wastewater management technologies (floating wetlands and an aerobic sequencing batch reactor (SBR)), and initiated community outreach with schools. The project also involved local authorities and government agencies in Kandy, and provided an informal cooperation platform. After project handover on July 10, 2014, further developments were observed in Kandy, including implementation of sewerage and centralised wastewater treatment, rehabilitation of Kandy Lake and the Mid-Canal, and integration of Kandy Lake into the city's development plan and regulations.

Membrane Technology for Water and Wastewater Management and Application in Egypt

Membrane Technology for Water and Wastewater Management and Application in Egypt

Source separation sewage systems as a trend in urban wastewater management: Drivers for the implementation of pilot areas in Northern Europe

Urban source separation infrastructure systems have a promising potential for a more sustainable management of household food waste and wastewaters. A renewed trend of larger implementations of pilot areas with such systems is currently emerging in Northern Europe. This study investigates the drivers behind the decision of stakeholders to implement source separation systems as well as the importance of the previously existing pilot areas in the decision-making process. By means of semi-structured expert interviews, five areas with source separation were characterized and compared. It was found that the most important drivers were on the one hand governmental, especially local environmental goals and on the other hand the ambition of the utilities to gain knowledge about future wastewater management and treatment technologies. Experiences from existing smaller pilot areas were shown crucial for decisions to implement the larger pilot areas that are currently planned, as was intensive stakeholder co-operation, due to the fact that source separation systems transcend traditional boundaries between energy, waste and water sectors. The results hold implications for policy makers and municipalities initiating a transition to more sustainable wastewater management.

The highly effective removal of Cs+ by low turbidity chitosan-grafted magnetic bentonite

Chitosan-grafted magnetic bentonite (CS-g-MB) was successfully synthesized via a plasma-induced method. The CS-g-MB composite shows good magnetic properties, low turbidity, and high stability in aqueous solution and exhibits significant adsorption capacity for Cs+ ions. The adsorption of Cs+ by CS-g-MB is dependent on both pH and ionic strength. In the presence of Mg2+, K+, Li+, and Na+ ions, the Cs+ exchange is constrained in the order of Li+≈Mg2+<Na+<K+, primarily as a result of the hydrated radii and hydration energies of these cations in aqueous solution. The stability of the CS-g-MB composite in simulated groundwater and in actual seawater was also investigated and this material was found to be a good candidate for the remediation of both types of water. These results demonstrate that enhanced coagulation achieved by plasma modification represents a viable yet advanced technology for wastewater management, and is capable of synthesizing new adsorbents that can be readily separated from solution and that avoid increasing the turbidity and color of the water being treated.

Cost-effectiveness of nitrogen mitigation by alternative household wastewater management technologies

Household wastewater, especially from conventional septic systems, is a major contributor to nitrogen pollution. Alternative household wastewater management technologies provide similar sewerage management services but their life cycle costs and nitrogen flow implications remain uncertain. This paper addresses two key questions: (1) what are the total costs, nitrogen mitigation potential, and cost-effectiveness of a range of conventional and alternative municipal wastewater treatment technologies, and (2) what uncertainties influence these outcomes and how can we improve our understanding of these technologies? We estimate a household nitrogen mass balance for various household wastewater treatment systems and combine this mass balance with life cycle cost assessment to calculate the cost-effectiveness of nitrogen mitigation, which we define as nitrogen removed from the local watershed. We apply our methods to Falmouth, MA, where failing septic systems have caused heightened eutrophication in local receiving water bodies. We find that flushing and dry (composting) urine-diversion toilets paired with conventional septic systems for greywater management demonstrate the lowest life cycle cost and highest cost-effectiveness (dollars per kilogram of nitrogen removed from the watershed). Composting toilets are also attractive options in some cases, particularly best-case nitrogen mitigation. Innovative/advanced septic systems designed for high-level nitrogen removal are cost-competitive options for newly constructed homes, except at their most expensive. A centralized wastewater treatment plant is the most expensive and least cost-effective option in all cases. Using a greywater recycling system with any treatment technology increases the cost without adding any nitrogen removal benefits. Sensitivity analysis shows that these results are robust considering a range of cases and uncertainties.

Evolution of Sanitation and Wastewater Technologies through the Centuries

Most of the technological developments relevant to water supply and wastewater date back to more than to five thousand years ago. These developments were driven by the necessity to make efficient use of natural resources, to make civilizations more resistant to destructive natural elements, and to improve the standards of life, both at public and private level. Rapid technological progress in the 20th century created a disregard for past sanitation and wastewater and stormwater technologies that were considered to be far behind the present ones. A great deal of unresolved problems in the developing world related to the wastewater management principles, such as the decentralization of the processes, the durability of the water projects, the cost effectiveness, and sustainability issues, such as protection from floods and droughts were intensified to an unprecedented degree. New problems have arisen such as the contamination of surface and groundwater. Naturally, intensification of unresolved problems has led to the reconsideration of successful past achievements. This retrospective view, based on archaeological, historical, and technical evidence, has shown two things: the similarity of physicochemical and biological principles with the present ones and the advanced level of wastewater engineering and management practices. Evolution of Sanitation and Wastewater Technologies through the Centuries presents and discusses the major achievements in the scientific fields of sanitation and hygienic water use systems throughout the millennia, and compares the water technological developments in several civilizations. It provides valuable insights into ancient wastewater and stormwater management technologies with their apparent characteristics of durability, adaptability to the environment, and sustainability. These technologies are the underpinning of modern achievements in sanitary engineering and wastewater management practices. It is the best proof that “the past is the key for the future”. Evolution of Sanitation and Wastewater Technologies through the Centuries is a textbook for undergraduate and graduate courses of Water Resources, Civil Engineering, Hydraulics, Ancient History, Archaeology, Environmental Management and is also a valuable resource for all researchers in the these fields. ISBN: 9781780404851 (eBook) ISBN: 9781780404844 (Print)

Experimental evaluation of anaerobic digestion for coffee wastewater treatment and its biomethane recovery potential

The objective of this study was to evaluate the performance of anaerobic digestion (AD) as an eco-friendly technology for coffee wastewater (CWW) management. First, we have characterized the CWW and found that it is suitable for microbial degradation with pH adjustment. Then, we designed a simple anaerobic batch reactor (ABR) and evaluated its potential for energy yield and efficiency to remove pollutants. The experiment was carried out by operating the anaerobic digestion (AD) for 70 days. The ABR was found to be efficient for the removal of organic load (90 %), nutrients (82 %) and suspended solids (95 %) from coffee processing waste. The increased removal efficiency of pollutants was dependent on the hydraulic retention time of the system. We also estimated that the coffee waste has a potential to produce a theoretical energy yield of 4–10 million KJ/day and an organic fertilizer (digestate) of 18.8–25.2 kg VSS/day. As a result, the AD would be a more sensible consideration as an eco-friendly treatment option for the coffee waste. The use of AD for CWW treatment not only reduces emission of greenhouse gases to the environment but also circumvents the rising demand for fuel wood and charcoal that causes a severe deforestation in the coffee growing regions of the world.