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Potential for treatment of household wastewater by using waste seashells as a biofilter media
Get PDFIn Norway, approximately 17% of the population is served by decentralized wastewater treatment systems. In these systems, a septic tank only is used, especially in those areas where sea is the final recipient of the treated water. In a septic tank, primary treatment takes place, which is not sufficient for removing pollutants as nutrients, organic matter and pathogens. To improve the quality of the effluent before its discharge, further treatment is required. To remove phosphorus, different kind of phosphorus sorbing materials such as Leca, Filtralite P, limestone, seashells, shell-sand etc. are available in the market. In Frøya Island, most single houses use a decentralized (on-site) wastewater treatment system consisting of a septic tank. Therefore, Frøya municipality is planning to update the existed wastewater treatment system on the entire island by using locally available filter materials. To reduce the investment cost, locally available material is considered used as a filter material. For this purpose three different kinds of sea-shells were investigated through a batch experiment in order to evaluate the phosphorus sorption capacity of each shell type.
Blue-shell, oyster and clam shell samples were collected in the first week of October 2017. Samples were prepared in three sizes (0-2, 2-4 and 4-8 mm) by the crushing and sieving. The batch experiment was performed in the laboratory of the soil section at NMBU. Two experimental set-ups were designed, one for blank analysis in which distilled water was used as a reactant and second for adsorption reactions in which 330 ppm phosphorous solution was used. Phosphorous contents were measured by spectrophotometer and sorbed phosphorus expressed as PO4-P.
The results of blank analysis showed very low values. Therefore, these values were not considered while calculating the final results of adsorption reactions. The batch experiment results represented that oyster shells had maximum sorption capacity and blue shells had minimum sorption capacity such as 7100 mg/kg and 520 mg/kg respectively. Comparatively, clam shells represented more or less similar sorption capacity like oyster shells, i.e. 6650 mg/kg. In addition, smaller sizes (0-2 mm) of all sea-shells showed maximum whereas, larger sizes (4-8 mm) showed minimum sorption capacity. Therefore, on the base of these results, it was concluded that oyster and blue shells have much higher potential for phosphorous removal from domestic wastewater than blue shells.
Based on the batch experiments, it was also calculated that 7.8 m3 of filter material is required for sorbing the phosphorus for 15 years from the wastewater produced by an individual Norwegian house with 5 people. It was also calculated, based on the batch experiments, that if all the septic tank effluents in Frøya filtered by crushed oyster shells, 221 m3 of crushed shells (2-4mm) would be needed per year to remove approximately 81% of the phosphorus. This is less than 15 truck-loads of 18m3/truck. Although, batch experiment results are reliable but they do not mimic the situation in a full scale filter receiving wastewater and, thus, are not sufficient to predict the real sorption and service life of seashells when applied as a filter material in systems receiving domestic wastewater. Batch experiment can only be feasible when comparing the filter materials and ranking them on the base of their phosphorus sorption capacity. Therefore, to more accurately predict the sorption capacity and service life of seashell based filter materials, large scale experiments with real wastewater are required
Environmental performance evaluation of decentralised wastewater treatment systems using life cycle analysis
No full textProper management of wastewater is a challenge for the cities in developing countries. The discharges of untreated wastewater into the urban rivers have huge impacts on public health as well as entire ecosystem of the earth. Therefore, treatment of wastewater is essential for the reduction of impacts on environment. Wastewater treatment plants remove the pollutant from the wastewater and thus reduce the pollutant load on the receiving water body. However the raw materials and energy required to build and operate the wastewater treatment systems also contribute to environmental burdens. Thereafter, the net environmental benefit of the wastewater treatment system can only be perceived by taking into account entire life cycle phases of the wastewater treatment system viz; construction, operation and demolition phases. In this study, Life Cycle Assessment (LCA) has been used as a tool for the sustainability assessment of small-scale decentralized wastewater treatment plants (WWTP) commonly used in developing countries. LCA is supportive to analyze the environmental burdens of WWTP that need to be a part of decision-making process towards sustainability. Life cycle assessment is known as cradle-to-grave analysis. LCA is a compilation and evaluation of the inputs, outputs and the potential environmental impact of a product system throughout its life cycle. The overall objective of the study is to analyze the environmental performance of the representative small-scale decentralized sanitation system.
In this study three-wastewater treatment scenario that consists of a combination of different small scale decentralized treatment methods are considered. The design capacities of the treatment modules used in the present study are 10 m3/day and 50 m3/day. The three Decentralized Wastewater Treatment (DEWATS) modules considered for the study are: 1) module 1 (DM1) consisting of Settler (S), Anaerobic Baffled Reactor (ABR), and Planted Gravel Filter (PGF), 2) module 2 (DM2) consisting of S, PGF and Collection Tank (CT) and 3) module 3 (DM3) consisting of S and PGF.
The Life Cycle Assessment was carried out as per ISO standards 14040-14044. In this study only the construction and operational phase was taken into account. The functional unit for this study is the treatment of wastewater generated by person equivalent over a period of 20 years.
In all modules, the greenhouse gas contribution (GWP) from the construction phase is 95% and 5% from operational stage. Acidification potential (AP) and Ozone layer depletion potential (ODP) are found to be 100% in construction periods. Among the treatment units, ABR has significant contribution to the eutrophication potential (EP). The other units like PGF, S and CT are responsible to the impact categories of AP, ODP and GWP. The study shows that configuration of the treatment units have an impact in the environmental performance. However, the more units the more environmental load is observed during the construction phase. On the other hand, increased in the units or treatment steps or modules increases the performance of system and hence decreases the environmental impacts of the whole system and vice versa. The production process of cement clinker, electricity, natural gas, brick, bituminous coal and transportation are responsible for the main impact during the construction phase. Based on the evaluation of three DEWATS modules, it cannot be said, which module is best, but the findings herein can support the decision-making process towards more sustainable DEWATS system.M-MIN
Sustainable sanitation in Upper Mustang (Nepal) : a case study in Lo Manthang Town
Get PDFIn Upper Mustang, one of Nepal's highest and most remote regions, sanitation infrastructure is undergoing major transitions. The area's inhabitants have traditionally been using dry toilets, perfectly adapted to the semi-arid Trans-Himalayan climate. Excreta are covered with ash from dung fires and reused on fields – the only fertilizer apart from animal manure in a place where about 90% of the people rely on subsistence agriculture and pastoralism. In recent years, however, guesthouses and schools have started building water toilets, which is problematic due to inadequate or non-existing wastewater treatment, posing a health risk and contaminating scarce water resources. Since living conditions in the area are very simple and health services limited, sustainable sanitation is crucial to avoid far-reaching problems.
A charity school in Upper Mustang's capital Lo Manthang is in the midst of these challenges: The school's dry toilets can no longer be used due to a lack of moisture-absorbing materials after switching from dung to gas as a cooking fuel. Meanwhile, the single functioning pour-flush toilet which was built instead is insufficient for the 40 resident students and staff and also causes unsolved issues with blackwater disposal. The objective of this thesis was to develop a sustainable sanitation system in cooperation with the school, aiming at a solution that would be considerate of the environmental conditions and available resources, culturally acceptable, affordable, and directed by local needs for long-term viability. In addition, general suggestions for sustainable sanitary improvements in the area are proposed, based on an assessment of the local context through a combination of social and natural science methods.
Among different options, the school chose to build five urine-diverting dry toilets, henceforth providing separate facilities for girls, boys and staff. When collecting urine and feces separately, only small amounts of amendments are needed to dehydrate and sanitize the pathogen-containing feces before reuse as soil conditioner on fields. The practically sterile, nutrient-rich urine can be applied to crops, for example to increase vegetable production. All materials and expertise for this technology are available in Nepal. For successful implementation, the school will need professional guidance and training of all users. Proper operation and maintenance will require a high degree of commitment, as will the safe handling and reuse of excreta, for which cooperation with farmers might be necessary. Furthermore, to improve the school's sanitary environment holistically, water supply and hygiene measures are essential: The current lack of running water will be addressed with a water storage system, three taps for hand-washing, three showers, and an infiltration trench for safe graywater disposal. The water quality of the town's public supply was found to comply with national standards. Through hygiene education and teachers as role models, students are likely to adopt hygiene habits for life.
For Lo Manthang, an awareness-raising program on the links between water, sanitation, hygiene, health and the environment is recommended, including information on the pros and cons of different sanitary options. Local households are advised to keep using dry toilets, and guesthouses may consider returning to dry sanitation as sewage disposal in leaching cesspools is not a long-term solution. Supplying excreta from dry toilets to farmers to cultivate organic produce could strengthen local livelihoods and serve to promote ecotourism. Clean public toilets, with urine diversion and/or solar dehydration, are suggested to reduce open defecation and demonstrate that dry toilets can look attractive – notions of "modernity" being one of the reasons why half of the local respondents prefer water toilets. However, while most welcome the idea of public toilets, only few would pay a user fee to ensure maintenance. To avoid water pollution, an infiltration system or constructed wetland should be built on the terrace of Lo Manthang to treat graywater – and blackwater if water toilets remain in use. The analyzed soils' hydraulic conductivity is low (2.2-8.3*10-5m/s), but purification will be good thanks to their calcium content sorbing phos-phorus and pathogens. Judging by the area's heterogeneous layered deposits, infiltration rates at other sites or greater depths will be higher. Effluent from a constructed wetland can be reused for irrigation.
Research challenges included constraints on finances and time in Upper Mustang. Moreover, stakeholder engagement at the school – though so crucial to create ownership – did not happen to the desired extent, probably related to differing expectations and priorities as well as limited experience with the participatory approach on all sides. In Lo Manthang, representative surveys will need to assess various stakeholders' attitudes towards ecological sanitation and wastewater treatment. The elaboration of designs and management schemes will require feasibility studies and further site investigations. However, the most important is the local people's initiative, involvement, and cooperation with sanitation experts.M-MIN
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Comparative assessment of a decentralized blackwater and organic household waste treatment system using LCA : Campus Ås showcase
Get PDFThis study evaluates the environmental performance of blackwater and organic household waste treatment in Campus Ås Showcase, located at the Norwegian University of Life Sciences, in Ås municipality, Norway. The Campus Ås Showcase is part of the SiEUGreen Project (www.sieugreen.eu) that aims to demonstrate that a combination of known and emerging technologies contributes to a more resilient and environmentally friendly urban development, with near zero emission, low water footprint and adoption of the circular economy concept.
In the Campus Ås Showcase, black water and organic household waste are collected from a dormitory, which is equipped with a vacuum toilet and a grinder system for organic waste. The treatment system comprises an anaerobic digestion reactor (AD), with recovery of biogas, and post-treatment methods that aim at plant nutrient recovery. The post-treatments are liquid fertilizer production (LF), struvite precipitation (SP) and microalgae cultivation (PBR). The systems demonstrated high efficiency of treatment and recovery of nutrients.
The analysis was carried out using the Life Cycle Assessment tool, described by ISO14040-44. The impact categories selected for analysis were the global warming potential (GWP), based on the 100-year potential, eutrophication potential (EP), water and energy consumption. The analysis was done for the construction and operational phase, and the fertilizer produced in the system was considered as an avoided burden of commercial fertilizer production. The results were compared to the conventional centralized treatment.
The results for the construction phase assessed the environmental impacts associated with the production of the materials used in the system under study. Only the main materials for each system were accounted for in this analysis. The production process of the stainless steel is responsible for the main impacts of the construction phase.
Two scenarios were evaluated. Scenario 1 comprises the AD, LF and PBR systems, and Scenario 2 includes struvite precipitation to the process. Scenario 1 presented better results in the GWP category than Scenario 2. The EP and the water consumption were similar for both scenarios. Scenario 2 consumed more energy due the addition of the struvite precipitation process. With the results, it is possible to infer that the addition of the struvite precipitation to the treatment process does not enhance the environmental performance of the system. However, it can be an interesting alternative in case the fertilizer should be transported from the production place.
The results of Scenario 1 were compared with the conventional treatment. The Nordre Follo Wastewater Treatment Plant was chosen for comparison and the operational data from the treatment plant was obtained. The anaerobic digestion treatment for organic waste is a theoretical set up. The comparative study has limitations as the technological representation of Campus Ås Showcase and the conventional system are not identical. Campus Ås Showcase demonstrated to have a better environmental performance with regards to GWP, EP and water consumption. On the other hand, the centralized system presented better results on energy consumption.
In the sensitivity analysis, the impact of the volume of flushing water used in the vacuum toilet on the performance of the system was investigated for Scenario 1. Volumes of 1 l, 0.75 l, 0.5 l and 0.25 were chosen. The results of the sensitivity analysis showed that the amount of biogas recovered can be increased significantly, as a result of a longer hydraulic retention time in the AD reactor. The liquid fertilizer produced had higher concentrations and lower volumes. There was not much difference from the results achieved in Scenario 1 in the categories GWP, EP and energy consumption. The water consumption decreased from 5.13 m^3 in Scenario 1 to 3.49 m^3, in the case of 0.25 l flushing volume.
Campus Ås Showcase demonstrated to be an environmentally friendly treatment process with low water consumption and of great potential for plant nutrient recovery and CO2 biofixation. To improve the system further, the biogas recovered can be used to supply heat to the AD reactor and it is also possible to complement the electricity source with solar power and decrease the tap water consumption with lower flush volume. To strengthen and validate the results of this study, it is recommended to conduct a LCA with the full-scale system once it is in full operation
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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