The synergy of permeable pavements and geothermal heat pumps for stormwater treatment and reuse

Use of municipal solid waste incineration (MSWI) bottom ash as a permeable subgrade material: An experimental and mechanism study

As a traditional method of waste treatment, municipal solid waste incineration (MSWI) has become one of the main methods of urban waste treatment. However, as a byproduct of MSWI, a large amount of MSWI bottom ash is not reused in current practice. This study innovatively posits MSWI bottom ash as an eco-friendly adsorbent rather than a pollutant, exploring its potential application as a permeable subgrade material. The results reveal that MSWI bottom ash exhibits promising properties to serve as a permeable subgrade material to achieve the permeability and improve the sustainability for subgrade. Due to the arrangement of its particles, it shows excellent performance in shear strength and permeability, which are comparable to or surpass those of sandy soils. The average pore width of 14.200 nm allows heavy metal substances to be encapsulated within the matrix, significantly reducing their leachability, thereby aligning with environmental friendliness standards. Its adsorption capacity is about 6.60 mg/g, and the adsorption capacity per volume is 3.66 times and 2.04 times that of fly ash and clay, respectively. The mechanism analysis shows that the adsorption process is monolayer heterogeneous adsorption. This paper presents a novel perspective on reusing MSWI bottom ash and provides evidence supporting its effective utilization as a permeable subgrade material, offering substantial environmental benefits through enhanced adsorption ability.Implications: Municipal solid waste incineration (MSWI) is a common method for municipal solid waste treatment, while the MSWI bottom ash is often not reused. This paper explored the explores the feasibility of using MSWI bottom ash as a permeable road base material. The results show that the particle arrangement enables excellent shear strength and permeability, comparable to sandy soil. It meets safety requirements for the leaching of heavy metals and acts as an adsorbent for pollutants leaching from permeable pavements. Furthermore, the mechanisms underlying these behaviors of MSWI were confirmed by microstructural and mineralogical analyses. These indicate that MSWI bottom ash has great potential as a permeable road base material. This paper provides a clear understanding of the physical, mechanical and environmental properties of MSWI bottom ash, which can promote its reuse in practice.

Energo- and exergo-technical assessment of ground-source heat pump systems for geothermal energy production from underground mines

The objective of this study is to perform the energy and exergy analysis of an integrated ground-source heat pump (GSHP) system, along with technical assessment, for geothermal energy production by deployment of Engineering Equation Solver (EES). The system comprises heat pump cycle and ground heat exchanger for extracting geothermal energy from underground mine water. A simultaneous energy and exergy analysis of the system is brought off. These analyses provided persuasive outcomes due to the use of an economic and green source of energy. The energetic coefficient of performance (COP) of the entire system is 2.33 and the exergy efficiency of the system is 28.6%. The exergetic efficiencies of the compressor, ground heat exchanger, evaporator, expansion valve, condenser and fan are computed to be 38%, 42%, 53%, 55%, 60% and 64%, respectively. In the numerical investigation, different alteration such as changing the temperature and pressure of the condenser show promising potential for further application of GSHPs. The outcomes of this research can be used for developing and designing novel coupled heat and power systems.

Measurement of Permeability and Comparison of Pavements

Permeable pavements have the ability to reduce surface runoff by allowing water to infiltrate into the underlying soil. The potential of permeable pavements to assist in managing stormwater and improve water quality has gained attention as an option, other than conventional impermeable concrete for paving purposes. This study examined the permeability of three different pavement systems, including the JW Eco-technology pavement (JW), which has not previously been installed or studied in the U.S., standard impermeable concrete (IC), and pervious concrete (PC). Each pavement type was installed in triplicate. Devices based on the ASTM C1701/C1701M and ASTM C1781/C1781M constant-head methods, the National Center for Asphalt Technology (NCAT) falling-head permeameter, and two new square frames, SF-4 and SF-9, modified to fit the JW pavement, were utilized for permeability measurement on several locations of each pavement system. The results showed that the JW Eco-technology pavement had comparable permeability to the commonly used PC pavement in each method used. In addition, there was a strong correlation between the permeability measurements of NCAT method and SF-4, and between the ASTM standard and SF-9. The square frames used in this study showed their effectiveness and efficiency in performing permeability measurements. It was also found that the permeability obtained had a pronounced difference in values between the falling head and the constant head methods, with an average ratio ranging from 4.08–6.36.

Application of stormwater collected from porous asphalt pavements for non-potable uses in buildings

This study assessed the potential for potable water savings in a building by using stormwater filtered by a porous asphalt pavement located in a parking lot. Stormwater is meant to be used for non-potable purposes (flushing toilets and urinals). Two models of porous pavement systems were constructed, both with porous asphalt mixture over a different combination of porous granular layers. The models were assessed for their filtering capacity; samples of stormwater runoff were collected in a parking lot located near the building where filtered stormwater is meant to be used. The models showed to be capable of filtering some pollutants. However, additional water treatment would be necessary to obtain the quality required for non-potable uses. Then one model was selected for a theoretical analysis on using it in a parking lot. The potential for potable water savings was analysed considering four scenarios as a function of daily local rainfall data. The thickness of the temporary stormwater reservoir layer was calculated in order to meet the design rainfall adopted, and the stormwater tank capacity was estimated using the Netuno computer programme. As a result, using a 45,000-litre stormwater tank, potable water savings of at least 53% would be obtained if filtered stormwater were used to flush toilets and urinals. This indicates that porous pavements show a great potential for filtering stormwater runoff to be used in buildings.

Rapid assessment system based on ecosystem services for retrofitting of sustainable drainage systems

Sustainable drainage systems (SuDS) design and retrofitting is predominantly based on expert opinion supported by descriptive guidance documents. The aim of this paper is to develop an innovative rapid decision support tool based on novel ecosystem service variables for retrofitting of key SuDS techniques. This unique tool proposes the retrofitting of a SuDS technique that obtained the highest ecosystem service score for a specific urban site. This approach contrasts with methods based on traditional civil engineering judgement linked to standard variables based on community and environment studies. For a case study area (Greater Manchester), a comparison with the traditional approach of determining community and environment variables indicates that permeable pavements, filter strips, swales, ponds, constructed wetlands and below-ground storage tanks are generally less preferred than infiltration trenches, soakaways and infiltration basins. However, permeable pavements and belowground storage tanks also received relatively high scores, because of their great potential impact in terms of water quality improvement and flood control, respectively. The application of the proposed methodology will lead to changes of the sustainable drainage infrastructure in the urban landscape.

Characteristics of run-off quality and pollution loading from a highway toll-gate

The Ministry of Environment of the Republic of Korea has been seriously considering implementing a TMDL (Total Maximum Daily Load) as a mandatory requirement on watersheds because of the potential water pollution from highway toll-gates. The purpose of this study was to investigate the characteristics of run-off quality and pollution loading during rainfall events at a highway toll-gate. Samples were analysed for run-off quantity and quality parameters such as COD(cr), TSS, total petroleum hydrocarbons, nutrients (TKN, NO3, TP and PO4) and several heavy metals (As, Cu, Cd, Ni, Pb and Zn). Based on a hydrograph and pollutant graph analysis, the pollutant concentration peak occurred in the run-off 10 minutes after the onset of rainfall. The typical first flush effect on the concentration depended on the rainfall intensity and the number of antecedent dry days. The relationships between the run-off and the event mean concentrations of the pollutants (e.g. TSS and COD) were described by general nonlinear equations. For governmental implementation of TMDL policies, the estimation of the cumulative TSS load was 1032 kg/(ha x yr) in 2007, 963.44 kg/(ha x yr) in 2008 and 847.21 kg/(ha x yr) in 2009. This information can lead to improved practical water quality management practices and reduced costs of improving water quality.