City-wide model-based analysis of heat recovery from wastewater using an uncertainty-based approach.

Around 90% of the energy requirement for urban water systems management is for heating domestic tap water. In addition, the energy content of wastewater is mainly in the form of heat (85%). Hence, there is an obvious interest in recovering a large portion of this heat. However, city-wide scenario analyses that evaluate heat recovery at various locations while considering impacts on wastewater treatment plant (WWTP) performance are currently very limited. This study presents a comprehensive model-based city-wide evaluation considering four different heat recovery locations (appliance, household, precinct and WWTP effluent) for a Swedish city with varying degrees of implementation using an uncertainty-based approach. Results show that heat recovery at the appliance level, with heat exchangers installed at 77% of the showers at domestic households, leads to a mean energy recovery of 127 MWh/day with a 0.25 °C reduction in mean WWTP inlet temperature compared to the default case without heat recovery. The highest mean temperature reduction compared to the default case is 1.5 °C when heat is recovered at the precinct level for 77% of the domestic wastewater flow rate. Finally, the impact on WWTP nitrification capacity is negligible in this case due to its large existing capacity and design.

Modelling temperature dynamics in sewer systems - comparing mechanistic and conceptual modelling approaches.

The vast majority of the energy consumed for urban water services is used to heat tap water. Heat recovery from wastewater is consequently an area of rapidly growing concern, both in research and by commercial interest, promoting the path towards a circular economy. To facilitate a system-wide evaluation of heat recovery from wastewater, this paper compares two one-dimensional models (mechanistic and conceptual) that can describe wastewater temperature dynamics in sewer pipe systems. The models are applied to successfully predict downstream wastewater temperature for sewer stretches in two Swedish cities (Linköping and Malmö). The root mean squared errors for the mechanistic model (Linköping Dataset1 - 0.33 °C; Linköping Dataset2 - 0.28 °C; Malmö - 0.40 °C) and the conceptual model (Linköping Dataset1 - 0.32 °C; Linköping Dataset2 - 0.20 °C; Malmö - 0.44 °C) indicate that both models have similar predictive capabilities, encouraging the use of conceptual models to reduce data requirements and model calibration efforts. Both models are freely distributed and can be easily integrated with wastewater generation and treatment models to facilitate system-wide wastewater temperature dynamics analysis.

Modelling heat recovery potential from household wastewater.

There is a strongly growing interest for wastewater heat recovery (WWHR) in Sweden and elsewhere, but a lack of adequate tools to determine downstream impacts due to the associated temperature drop. The heat recovery potential and associated temperature drop after heat recovery on a building level is modelled for a case study in Linköping, Sweden. The maximum temperature drop reaches 4.2 °C, with an annual recovered heat of 0.65 kWh · person-1 · day-1. Wastewater temperature out from the heat exchanger was 18.0 °C in winter at the lowest. The drinking water source type can be an important factor when considering wastewater heat recovery.

Urinary continence appears to enhance social participation and intimate relations in adolescents with myelomeningocele.

INTRODUCTION: The majority of adults with myelomeningocele (MMC) in Western Sweden use incontinence pads. There is an ongoing discussion as to whether continence improves the quality of life (QoL) in individuals with MMC as it has been hard to establish that an increase in QoL measured by generic health-related quality of life (HRQoL) instruments is achieved by continence surgery. OBJECTIVE: The hypotheses are that patients who are actively involved in a urotherapy/urology program are more continent than patients who are not and that urinary continence is one of the conditions required to enable social participation and physical intimacy. STUDY DESIGN: All 25 individuals in Western Sweden with MMC (15 males) aged 16-18 years were involved in this cross-sectional, prospectively designed study of urinary and fecal continence. During interviews, questions were asked about the following: clean intermittent catheterization (CIC) and bowel regimens, the need for reminders or help from an assistant, social participation, and physical intimacy with a partner. RESULTS: In the group, overall 17 of 25 (68%) had achieved urinary continence, 19 of 25 (76%) had a medical history of fecal continence, and 14 of 25 (56%) had no prescription for incontinence pads. Those who were urinary continent (17) included all nine patients who had received continence surgery in addition to six patients taking anticholinergics and two following the CIC procedure only. Urinary incontinence due to sphincter insufficiency was found in eight individuals, all of whom declined surgical treatment. All individuals (25/25) physically catheterized themselves, and 15/25 (60%) performed the fecal elimination regimen independently. Twelve individuals participated actively in social life, and eight of them had, or had had, a partner. All these 12 were urinary continent, and all but one were able to follow a fecal elimination regimen independently. Three of the 12 said they were fecal incontinent but knew how to become continent by following the prescribed fecal elimination regimen. DISCUSSION: Studies in this patient group have shown that incontinence means that it's harder to live a healthy adult life. Children too worry about incontinence episodes at school, and 70% consider urinary incontinence a problem. A limitation in the study is the small population, something often seen in rare diseases. CONCLUSIONS: With standardized follow-up, active treatment strategy and uro/bowel therapy, the urinary continence rate in adolescents with MMC at the study center is high compared with adults with MMC in Sweden. It appears that urinary continence is important in enabling successful participation in social life and in intimate physical relations with others.

Dynamic modelling of nitrous oxide emissions from three Swedish sludge liquor treatment systems.

The objective of this paper is to model the dynamics and validate the results of nitrous oxide (N2O) emissions from three Swedish nitrifying/denitrifying, nitritation and anammox systems treating real anaerobic digester sludge liquor. The Activated Sludge Model No. 1 is extended to describe N2O production by both heterotrophic and autotrophic denitrification. In addition, mass transfer equations are implemented to characterize the dynamics of N2O in the water and the gas phases. The biochemical model is simulated and validated for two hydraulic patterns: (1) a sequencing batch reactor; and (2) a moving-bed biofilm reactor. Results show that the calibrated model is partly capable of reproducing the behaviour of N2O as well as the nitritation/nitrification/denitrification dynamics. However, the results emphasize that additional work is required before N2O emissions from sludge liquor treatment plants can be generally predicted with high certainty by simulations. Continued efforts should focus on determining the switching conditions for different N2O formation pathways and, if full-scale data are used, more detailed modelling of the measurement devices might improve the conclusions that can be drawn.