Screening of chemical oxidation processes and other methods for decolorization of urine for its re-use as toilet-flush liquid in ecological sanitation systems.

Because of its potential use as fertilizer, urine ("yellow water") is a resource originating from sanitation. Its separate collection in no-mix toilets is a beneficial aspect of ecological (source control) sanitation. In order to avoid dilution of the fertilizing nutrients with toilet flush water, the utilization of yellow water as toilet flush liquid seems to be advantageous. To be accepted for this purpose, urine has to be decolorized (and also deodorized). In this study activated carbon adsorption, irradiation with UV light of different wavelengths, the advanced oxidation processes ultrasound, UV/H2O2, and photocatalytic oxidation have failed to decolorize urine. Biological treatment caused brown colour of the treated urine. Only ozonation was successful in colour removal, although it did not affect TOC. In spite of darkening of yellow water during biological treatment (generation of humic substances), smaller ozone doses were required for decolorizing the biologically pre-treated urine than for original urine. Photocatalytic oxidation of biologically treated urine also removed brown colour, but the original yellow colour remained. In ozonated urine, yellow colour was reconstituted unless hydrogen peroxide was added. In addition to colour removal, ozone contributed to deodorization as a consequence of ammonia stripping and probably of phenol oxidation.     

A sustainable approach towards rural development: dry toilets in Nepal.

Existing inadequate sewerage systems and direct disposal of household waste into water courses has tremendously increased water pollution. Dry toilets are feasible in rural and peri-urban areas to reduce the consumption of costlier water that is required for flushing. As conventional treatment technologies require high investment, and operation and maintenance costs, dry toilets are the only suitable option left for sanitation in the 21st century when working with limited financial resources. To reduce environmental degradation and overcome this problem, the dry toilet is only the realistic option in Nepal. Two reactors, one exposed to sunrays and the other without sunrays, were constructed. In the model with sunrays, it was found that in 48 days of observation faecal coliform presence depleted to 610 cells per gm from the initial value of 7 x 10(10) and volatile organic matter came down from 98.09% to 70.18%. Similarly, in the other model, the destruction of faecal coliform in 65 days was found to be 920 cells/gm while the destruction of organic matter took 75 days. Also, observing from 313 people in a cluster on the pilot project, the annually recovered value of N, P and K was found to be 1565 kg, 125 kg, 344 kg, respectively. This paper deals with the different types of dry ecological toilet, their performance and feasibility study in Nepal, with the full involvement of local people, based on complete laboratory analysis and regular monitoring. Using dry toilets will save 14 LPCD, which is equivalent to 14 MLD and the resulting demand will become only 80 MLD for the urban area of Kathmandu. The result advocates the implementation of ecological dry toilets to save valuable water wasted in flushing, as well as saving the resources needed to treat the waste.     

On-site sanitation: a viable alternative to modern wastewater treatment plants.

Rapid population growth and urbanization are exerting excessive pressure on soil and water resources. To address these problems this paper proposes a cheap and sustainable alternative sanitation system, which accelerates nutrient recycling ("closing the loop"): ecological sanitation (ecosan) is a potential alternative to conventional sanitation systems that replenishes the organic matter and nutrients of the soil that are taken off as the crop harvest. A comparison is made of the environmental and the operation and maintenance costs between a modern wastewater treatment plant and on-site sanitation. An elevated double box urine diverting toilet ("ecotoilet") is proposed and its advantages and disadvantages over a system with a centrally controlled modern WWTP are discussed. Bagmati Area Sewerage Project in Kathmandu is taken as an example of modern WWTP and ecosan being practiced in a village in Nepal is taken as an example of ecotoilet for the comparison.     

Economic viability and critical influencing factors assessment of black water and grey water source-separation sanitation system

The black water and grey water source-separation sanitation system aims at efficient use of energy (biogas), water and nutrients but currently lacks evidence of economic viability to be considered a credible alternative to the conventional system. This study intends to demonstrate economic viability, identify main cost contributors and assess critical influencing factors. A technico-economic model was built based on a new neighbourhood in a Canadian context. Three implementation scales of source-separation system are defined: 500, 5,000 and 50,000 inhabitants. The results show that the source-separation system is 33% to 118% more costly than the conventional system, with the larger cost differential obtained by lower source-separation system implementation scales. A sensitivity analysis demonstrates that vacuum toilet flow reduction from 1.0 to 0.25 L/flush decreases source-separation system cost between 23 and 27%. It also shows that high resource costs can be beneficial or unfavourable to the source-separation system depending on whether the vacuum toilet flow is low or normal. Therefore, the future of this configuration of the source-separation system lies mainly in vacuum toilet flow reduction or the introduction of new efficient effluent volume reduction processes (e.g. reverse osmosis).     

污水灌溉与污水土地处理系统在公厕污水处理中的应用

位于昆明市下游的滇池,因受市区排放的生活污水、工业废水以及当地污水的影响,水污染问题十分突出,急需治理。污水灌溉与污水处理相结合的土地系统是一种可供选择的技术措施。本文阐述了将该系统用于公厕污水处理的工程构造型式与运行管理方式,建立了示范应用工程,开展了污染物去除效果研究和效益分析。结果表明,采用污水灌溉与污水土地处理系统处理公厕污水,处理后回用于厕所冲洗,可获得良好的污水处理效果,并可节约宝贵的淡水资源。该技术在实际应用中具有经济可行性。     

EU demonstration project for separate discharge and treatment of urine, faeces and greywater--part I: results.

The main aim of this EU demonstration project was to test two new sanitation concepts to determine if these concepts are more sustainable, compared with the conventional sanitation system, particularly with regard to nutrient recycling. Two different sanitation concepts were tested. One concept comprised the use of gravity separation toilets, the other used vacuum separation toilets. Results from a life-cycle-assessment investigation show that the new sanitation concepts are more sustainable. A cost analysis for an existing residential area did not prove lower costs for the new sanitation concepts in this special case. The experience from this demonstration project shows that prior to a widespread use of the new sanitation concepts, several improvements have to be made. One important issue is the improvement of separation toilets. Since nutrient recycling, water saving and reuse as well energy reduction become more and more important, further research should be undertaken in this field.     

锁金山水电站技术供水系统改造

论述了锁金山水电站技术供水系统改造工程实况,包括设置进水口自动清污机、选择新的供水泵、改造供水管网、更新管道滤水器等项目。供水系统改造投入使用后,经过近2 a的运行检验,其工作可靠性高,运行方式灵活,维护工作量小,运行成本低,取得了较好的效果。     

Young users accept NoMix toilets--a questionnaire survey on urine source separating toilets in a college in Switzerland.

We studied user behavior and acceptance of NoMix toilets by collecting 271 questionnaires from young adults. We discriminated between short- and long-term users (months of habituation). Most respondents noticed that the NoMix toilet is different. Nevertheless, the existing NoMix technology was well accepted regarding design, hygiene and smell in this institutional setting. Only few respondents changed their sitting or flushing behavior. The necessity to sit when urinating might be slightly problematic (62% sit), but it seems possible that people adopt this new behavior required by the NoMix toilet. General acceptance of the NoMix toilet was high: 70% of respondents found the idea convincing--many for environmental reasons--87% were willing to move into an apartment with a NoMix toilet, and 20% would pay substantially more for a NoMix toilet. We informed about the NoMix toilet with instructions for use in the toilet cabin, an information poster, and an information leaflet that we distributed after questioning. Our information was noted by most respondents and significantly increased the knowledge about and the acceptance of the NoMix toilet. We recommend that future pilot projects with NoMix toilets consider a well devised information policy to support decision making and acceptance of this new technology.     

Modelling anaerobic digestion of concentrated black water and faecal matter in accumulation system

A dynamic mathematical model based on anaerobic digestion model no. 1 (ADM1) was developed for accumulation (AC) system treating concentrated black water and faecal matter at different temperatures. The AC system was investigated for the treatment of waste (water) produced from the following systems: vacuum toilet for black water (VBW), vacuum toilet for faeces with urine separation (VF), dry toilet (DT), dry toilets for faeces with urine separation (DF), separated faecal matter from conventional black water by filter bag (FB). For evaluation of the AC system treating the proposed waste (water) sources at 20 and 35 degrees C, two options were studied: (1) The filling period of the AC system was constant for all waste (water) sources (either 1, 3 or 6 months) and for each period, the seed sludge volume was varied; (2) The volume of the AC system was constant for all proposed waste (water) sources. The results showed that the filling period of the AC system was the main parameter affecting the system performance, followed by operational temperature, while the increase of the seed sludge volume slightly enhanced the performance of the system. The model results indicated that the filling period of the AC system should be higher than 150 days for obtaining a stable performance. It was found that the hydrolysis of biodegradable particulate chemical oxygen demand (COD) is the rate limiting step, as volatile fatty acid concentration is very low in all experimental conditions (< 200 mgCOD/L at 20 degrees C and < 100 mgCOD/L at 35 degrees C). Based on the results of the two options, it was found that the concentrated waste (water) sources have better performance than the diluted waste (water) sources, like VBW waste (water). Furthermore, smaller volume will be required for the AC system.     

Technology selection and comparative performance of source-separating wastewater management systems in Sweden and The Netherlands.

The research described in this paper has evaluated five demonstration projects with source-separating sanitation at neighbourhood scale, 10 years or more after their establishment. It presents the results of two systems with local grey water treatment in The Netherlands and three sites with urine separation in Sweden. The study has focused on (1) the drivers and barriers of the stakeholders that were responsible for project implementation and (2) the comparative performance of the source separation systems after their establishment. In The Netherlands the main drivers were water use reduction, combating sewer overflows and reduction of emissions. For the Swedish cases the main drivers of the involved actors were nutrient recycling, emission reduction and an active policy of the local government. The main barriers in all cases were higher investment costs and low experience with new sanitation approaches systems compared with the conventional system. Three of the sites showed a lower performance with respect to public health because effluent monitoring protocols for the grey water treatment systems were not in place or people could have direct contact with faeces. Lack of operation and maintenance is a cause of occasional failure for the grey water treatment systems, while the dominant failure reason for the urine separation systems was pipe clogging. The inventory showed that source-separating sanitation systems have a high potential to save or recover resources (water and nutrients).     

Separation efficiency in a whirlpool surface tension separator, separating faeces and toilet paper for nutrient recovery--pilot-scale study.

The main proportion of the plant nutrients in waste from society can be recycled in two unpolluted fractions if the urine and the faeces are collected separately. By using urine-diverting toilets combined with a whirlpool surface tension faecal separator, it is possible to achieve this. If the separator is installed correctly, with a gradual bend to minimise disintegration of the particles, it is possible to collect approximately 92% nitrogen, 86% phosphorus and 76% potassium of the content excreted in the faeces in a small separated fraction that only contains 10% of the flushwater used. The faecal separation is a robust system with no moving parts, which is not significantly affected by the flushwater volume, and almost no water is separated to the separated solids if neither toilet paper nor faeces are flushed.     

Decision-making criteria and indicators for water and sanitation projects in developing countries

Water and sanitation projects for solving the needs of small communities in developing countries are complex in nature and involve complex decision-making, which must consider technical, socioeconomic and environmental dimensions. Multicriteria analysis (MCA) is a suitable decision-aid method that scores a finite number of options on the basis of a set of evaluation criteria. The main challenge in MCA is choosing the appropriate criteria and evaluation indicators to use for assessment. The aim of this paper is to present a comprehensive and wide list of criteria and evaluation indicators as a guideline in MCA of water and basic sanitation projects in small rural communities of developing countries. First, the paper details the general criteria to be considered in all the projects, which are classified in to 4 main groups: technical (e.g., local resources use, appropriate management); social (e.g., local community participation, overcoming discrimination of conflict); economic (e.g., low cost, employment of local staff) and environmental criteria (e.g., atmospheric emissions, water pollution). Then, it describes technical criteria to be additionally considered in each specific type of project: water supply (e.g., water needs, independent access), water treatment (e.g., constant resource availability, flexibility of use for different types of water) and basic sanitation projects (e.g., maximum number of people per system, effluent quality).     

A Financial,Environmental and Social Evaluation of Domestic Water Management Options in the West Bank,Palestine

Water is one of the most valuable natural resources in the West Bank, Palestine. Due to its limited availability, it is a resource that needs particular protection. Although agriculture consumes most of the water (70%) in the West Bank, the domestic water supply is strategically not less important. It is the aim of this study to evaluate domestic water management options suitable for Palestinian conditions that contribute to achieving water sufficiency in the domestic water use in the house of tomorrow. A number of options were evaluated economically, environmentally and socially using the concept of life cycle impact assessment (LCIA). Results of the study showed that by introducing a combination of domestic water management options, a substantial decrease in the water consumption of more than 50% can be achieved, thereby reducing the pressure on the scarce water resources. The annual environmental impact of the in-house water use can be reduced in the range of 8%, when using low-flow shower head to 38% when using rainwater harvesting systems. Some of the options (faucet aerators, low-flow shower heads and dual flush toilets) were found to be financially attractive with a pay back period of less than their expected lives, others (rainwater harvesting, graywater reuse and dry toilets) were found to be financially unattractive because of the high investment. In the social context, it was found that introducing such options can improve the quality of life of those not having enough water. There is already a popular willingness to take part in water conservation in the domestic sector in the West Bank. The strongest driving force for using water conservation measures is the awareness that water is a scarce resource. It was concluded that, theoretically, the house of tomorrow can be largely independent in terms of water and sanitation. Education and awareness campaigns in the context of water management with a focus on non-traditional options are key to achieve such a house.     

Assessment of Potable Water Savings in Office Buildings Considering Embodied Energy

The objective of this article is to assess the potential for potable water savings in office buildings located in Florianópolis, southern Brazil. The embodied energy of four alternatives to reduce potable water demand, i.e., rainwater harvesting, greywater reuse, dual-flush toilets and water-saving taps, was also assessed. The analyses took into account the potable water end-uses for ten buildings. The potential for potable water savings by using rainwater, as well as, the rainwater tank sizing were estimated using computer simulation. As for greywater reuse, it was considered that greywater from lavatory taps could be treated and reused to flush toilets. The potential for potable water savings by using water-saving plumbing fixtures was estimated by considering the replacement of toilets and taps. In order to estimate the embodied energy in the main components, each system was dimensioned and embodied energy indices were applied. The main result is that the potential for potable water savings by using dual-flush toilets ranges from 21.6 % to 57.4 %; by reusing greywater, it ranges from 6.8 % to 38.4 %; by using rainwater, it ranges from 6.1 % to 21.2 %; by using water-saving taps it ranges from 2.7 % to 15.4 %. However, by considering the embodied energy, the average for the ten buildings indicates that dual-flush toilets are the best choice as it is possible to obtain water savings of 5.50 m³/month per GJ of embodied energy, followed, respectively, by water-saving taps, greywater reuse and rainwater usage. The main conclusion is that the assessment of embodied energy should be considered when evaluating potable water savings in buildings as it helps to identify the best alternatives to save more water while causing less environmental impact.     

回转式清污机在宁夏大型灌排泵站的应用

回转式清污机清污量大，操作方便，对泵站设备安全运行起着至关重要的作用。本文介绍了HQN型回转式清污机的结构型式、工作原理、基本技术要求、技术参数，以及运行情况和效果分析。     

Decentralized collection of iodinated x-ray contrast media in hospitals-results of the feasibility study and the practice test phase

Iodinated x-ray contrast media are unmetabolized and almost completely with the urine in 24 hours emitted in the wastewater after their application by human being. These very polar, hydrophilic and hardly biodegradable substances have already been detected in the water cycle. The objective of this R&D project is the collection of the x-ray contrast media already at the source in the hospital and so the avoidance of an emission in the water cycle.Three concepts have been developed in the scope of this R&D project: a centralized collection concept with a no-mix toilet in the radiology unit, a decentralized collection concept featuring a no-mix toilet for every of the ward and another decentralized collection concept with mobile urine containers for the wards. The evaluation of the collection concepts has taken systematically into consideration costs, acceptance and a value benefit analysis. The feasibility study has shown that a separated collection of iodinated x-ray contrast media in hospitals is possible through the implementation of a decentralized urine collection concept using mobile urine containers.This decentralised collection concept was tested in each case on one main focus ward of two representative German hospitals for 20 weeks. In both wards of the hospitals around 60% of patients with an examination of x-ray contrast media took part in the voluntary urine collection. The AOX arose from the iodinated x-ray contrast media in the collected urine. The averaged measured AOI concentration in the patient's urine was 18 g/l. The total costs, formed by the costs for staff, material and disposal, were estimated at 10 euro per patient, 7 euro per litre urine and approximate 380 euro per kilogramme iodine for the separated urine collection in hospitals. The main part of the total costs is formed by the costs for staff with around 80%.This R&D project has shown that the separated collection of the patients' urine with a simple and decentralised collection concept with mobile urine containers in hospitals can be carried out hygienically and safely. A transfer of this decentralised collection concept to pharmaceuticals which are excreted with urine is possible.     

液相中地下水对过氧化氢稳定性的影响

某型装置工作前,需用大量去离子水浸泡。为简化清洗程序,减轻装备运行、维护负担,有必要探讨采用其他容易获得的普通水替代去离子水作为清洗液的可能。该文假定以新疆地区地下水为清洗液,将其与90%过氧化氢溶液按0.2%、0.4%(V/V)比例混合,模拟了残留清洗液对过氧化氢稳定性的影响。采用高锰酸钾氧化还原滴定法,在7d和13d的时间跨度内测定了过氧化氢浓度随时间的变化情况。结果表明,液相中少量地下水对过氧化氢稳定性没有影响。     

住宅区生态卫生排水系统技术和费用效益评价

生态卫生排水系统通过污染源的分类收集,并进行循环利用,其系统构成具有可持续性.针对内蒙古自治区鄂尔多斯市郝兆奎生态小区生态卫生排水(源分离)系统工程,分析了住宅区生态卫生排水系统的技术特征,同时对技术的适用性进行了调查.结果表明,住宅区生态卫生排水系统在技术上基本可行.采用费用效益法,当社会折现率为8%时,郝兆奎生态小区生态卫生排水系统经济净现值(ENPV)大于零,项目经济可行.     

Treatment of toilet wastewater for reuse in a membrane bioreactor.

Toilet wastewater is treated and reused on site at Europe's highest membrane bioreactor (MBR), located in a cable car mountain station in the ski resort of Zermatt. Negative impacts on the sensitive mountain environment are minimised by reusing close to 100% of the treated wastewater for toilet flushing. Besides 100% nitrogen removal, 80% of phosphorus was also eliminated. This paper presents operational results, optimisations of sludge management, decoloration and long-term maintenance of biomass in the very low-loaded summer season. From a global view the experiences and results of the project are of great importance, proposing a solution to a problem existing 100-fold in the Alps as well as in arid regions all over the world: reducing water consumption for sanitation by reuse.     

A performance investigation of small-bore sewers.

This paper describes a full-scale physical model and its application to investigate the effectiveness/performance of small-bore sewers for a range of operational and design parameters. The implementation methodology involves observing the movement of synthetic gross solids in three small bore sewers (150, 100 and 75 mm diameter) for different volumes of simulated flush waves and gradients. The simulated flush waves were generated, using an automated wave sequencer, for three different flush volumes (3, 4.5 and 6 litres). To investigate the impact of solid shape factor, a number of tests were carried out using synthetic solids in combination with toilet tissue paper. In total, more than 1,000 tests were performed for different operational and design parameter combinations. Results obtained to date have confirmed earlier studies, particularly with respect to the role of flush volume in solids transport, and identified the impact of gradient variation and its significance particularly in small-bore sewers receiving low flush volume. Results from the physical model application exercise will be used to propose new design guidelines for wastewater collection systems with specific consideration to new developments and inform the decision support system, currently being developed as part of a research project on water cycle management for new developments (WaND).