Quantifying future sanitation scenarios and progress towards SDG targets in the shared socioeconomic pathways.

Two main targets of SDG 6 (Sustainable Development Goal), clean water and sanitation, are SDG 6.2, to achieve universal and equitable access to improved sanitation and to phase out unimproved sanitation (include pit latrines without a slab or platform, hanging latrines, bucket latrines and open defecation) and SDG 6.3, to halve the proportion of untreated wastewater by 2030. We compiled a global sanitation database for 200 countries. Starting from recent trends, we constructed a wide spectrum of contrasting future scenarios, i.e. the five Shared Socio-economic Pathways (SSP1-5) whereby the SSP2 scenario is 'middle of the road' scenario. The sanitation scenarios differ due to contrasting pathways for population growth and urbanization, economic growth and the SSP narratives. Our results indicate that it will be difficult to achieve the SDG 6 target. Target 6.2 on improved sanitation is expected to be achieved between 2070 and 2090 in SSP1, SSP2 and SSP5, while the target will not be achieved by 2100 in SSP3 and SSP4. Unimproved sanitation is projected to be phased out by 2070 in SSP1 and SSP5, or beyond 2100 in SSP3 and SSP4. The percentage of households with sewerage connection will be between 51% in SSP3 and 75% in SSP5 in 2050, and respectively 60% and 95% in 2100. Target SDG 6.3 on improving wastewater treatment will be reached by 2030 only in SSP1, followed by SSP2 and SSP5 between 2040 and 2050, while in SSP3 and SSP4 this target is not reached by 2100. The developments in wastewater treatment, expressed as percentage nutrient removal, showed an increase from 14% in 2015 to 45% in 2050 and 80% in 2100 in SSP1. But in SSP3, the global percentage is expected to have hardly changed by 2050 and have declined to 12% by 2100 due to the population growth in Sub-Saharan Africa. There is a major contrast between countries and regions. In the period between 2000 and 2015, although globally the percentage of people with unimproved sanitation declined, in 7% of the 200 countries the number of people with unimproved sanitation increased. Also, wastewater treatment globally improved, but in 16 countries it deteriorated. This inequality is particularly important in SSP3 and SSP4 where the lack of improved sanitation will continue till 2100.

Global nitrogen and phosphorus in urban waste water based on the Shared Socio-economic pathways.

This paper presents global estimates of nutrient discharge from households to surface water based on the relationships between income and human emissions represented by protein consumption, degree of connection to sewerage systems, presence of wastewater treatment plants and their level of nutrient removal efficiency. These relationships were used to construct scenarios for discharge of nutrients with waste water based on the five Shared Socio-economic Pathways for the period from 1970 to 2050. The number of inhabitants connected to a sewerage system will increase by 2-4 billion people between 2010 and 2050. Despite the enhanced nutrient removal by wastewater treatment, which will increase by 10%-40% between 2010 and 2050, nutrient discharge to surface water will increase in all scenarios by 10%-70% (from 10.4 Tg nitrogen (N) in 2010 to 13.5-17.9 Tg N by 2050 and from 1.5 Tg phosphorus (P) in 2010 to 1.6-2.4 Tg P by 2050). In most developing countries, nutrient discharge to surface water will strongly increase over the next decades, and in developed countries it will stabilize or decrease slightly. A global decrease in nutrient discharge is possible only when wastewater treatment plants are extended with at least tertiary treatment in developing countries and with advanced treatment in the developed countries. In future urban areas that will be developed over the 2010-2050 period, options for recycling can be included in wastewater management systems. A separate collection system for urine can yield 15 Tg N yr-1 and 1.2 Tg P yr-1, which can be made available for recycling in agriculture. The SDG 6.3 about safely treated waste water by 2030 will be reached in the developed countries in 2030. In the developing countries, the goal will be reached by 2050 only under SSP1, SSP2 and SSP5.

Datasets of the phosphorus content in laundry and dishwasher detergents.

This data article provides the data of Phosphorus emissions from laundry and dishwasher detergents as part of the Phosphorus emissions from households. The household emissions are presented in the research article "Global nitrogen and phosphorus in urban waste water based on the Shared Socio-economic pathway" (van Puijenbroek et al., 2019) [1]. Laundry and dishwasher detergents are a major source of phosphorus loading of aquatic ecosystems in countries with a substantial use of laundry and dishwasher machines. In this article, datasets are presented with the global use of laundry and dishwasher detergents and the Phosphorus emissions due to laundry and dishwasher detergents. These results are presented for 10 world regions for 1970 and 2010, and for 2050 with 5 Shared Socio-economic Pathways. The outlook results for 2050 were based on the growth in income and population and on environmental policy for the introduction of Phosphorus free detergents.

Global implementation of two shared socioeconomic pathways for future sanitation and wastewater flows.

Households are an important source of nutrient loading to surface water. Sewage systems without or with only primary wastewater treatment are major polluters of surface water. Future emission levels will depend on population growth, urbanisation, increases in income and investments in sanitation, sewage systems and wastewater treatment plants. This study presents the results for two possible shared socioeconomic pathways (SSPs). SSP1 is a scenario that includes improvement of wastewater treatment and SSP3 does not include such improvement, with fewer investments and a higher population growth. The main drivers for the nutrient emission model are population growth, income growth and urbanisation. Under the SSP1 scenario, 5.7 billion people will be connected to a sewage system and for SSP3 this is 5 billion. Nitrogen and phosphorus emissions increase by about 70% under both SSP scenarios, with the largest increase in SSP1. South Asia and Africa have the largest emission increases, in the developed countries decrease the nutrient emissions. The higher emission level poses a risk to ecosystem services.

Towards standardised evaluative measurement of nature impacts: two spatial planning case studies for major Dutch lakes.

In the assessment of complex spatial planning projects, the ecological impacts and socio-economic impacts are fundamental to the evaluation. The measurements of ecological impacts of spatial plans have to be integrated in a standardised way. In the present paper, we analyse two Dutch case studies and apply the standardised Threat-Weighted Ecological Quality Area measurement. This measurement is developed to evaluate projects with terrestrial impacts but has not yet been applied for water evaluations. We aim to show how the use of a common measurement tool incorporates both ecological quality and degree of threat on criteria in the EU Water Framework Directive and Nature 2000. The measurements discussed here derive from two cases of cost-benefit analysis: The first case is the Markermeer, the second largest lake of The Netherlands, and a study on water quality improvement and nature restoration; an artificial island will also be the setting for a new residential area. The second case study is on water level management carried out on the IJsselmeer, the largest lake in the country. Results of our analysis show the potential impacts with a standardised method to the spatial distribution and quality of the ecosystems.

Global trends and uncertainties in terrestrial denitrification and N2O emissions.

Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900-2000 and scenarios for the period 2000-2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr(-1) (Tg = teragram; 1 Tg = 10(12) g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408-510 Tg N yr(-1) by 2050. In the period 1900-2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr(-1), and this may remain stable or further increase to 275 Tg yr(-1) by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr(-1) between 1900 and 2000, and N2O-N emissions from 10 to 12 Tg N yr(-1). The scenarios foresee a further increase to 142 Tg N2-N and 16 Tg N2O-N yr(-1) by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O-N yr(-1) in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans.