The worldwide increasing amount of municipal solid waste causes a major problem in managing waste as well as requires an effective solution to manage the waste generation. In Malaysia, landfilling is the main alternative technique for managing solid waste. In the same way, the main advantage of having a landfill is that it is easy to operate and comparatively lower in cost. Thus, in Malaysia, total 296 municipal solid waste landfills are open to overcome this issue. Drawbacks of landfilling can includes; i) generation of noxious gases, ii) leachate wastewater contamination of both ground and surface water, iii) problems such as odor, noise, and dust, iv) attraction of disease vectors and, v) the requirement for considerable land area. This present research study focuses on the characterization of Simpang Renggam Landfill (SRLS) Site such as its organic constitutes (mg/L), Ammoniacal Nitrogen (mg/L), SS (mg/L), BOD5/COD, BOD5 (mg/L), and pH. All the analyzed results were compared with the past researchers’ researches and also were compared with Malaysian Environmental Quality Act 1974. From the results, it is concluded that the Simpang Renggam Landfill Site was characterized old (stabilized) landfill leachate wastewater with BOD5/COD > 0.1. For the SRL site, it is recommended that physical-chemical method is better fitted for the leachate wastewater treatment and the aerated lagoon technique does not support the treatment of aging leachate.

This study aims to establish the optimal percentage of water treatment sludge (WTS) for incorporation into fired clay bricks, assessing both physical and mechanical properties as well as heavy metal leachability. Fired bricks were produced with varying proportions of WTS (0%, 5%, 10%, 20%, and 30%). Compressive strength, density, shrinkage, and water absorption were examined to evaluate physical and mechanical properties. Toxicity Characteristic Leaching Procedure was employed to investigate heavy metal concentrations, focusing on inorganic constituents. Results indicated that the optimal ratio for WTS in fired clay bricks is 5%, aligning with industry standards (BS 3921:1985). The 5% sludge incorporation yielded bricks with impressive attributes: a peak compressive strength of 25.40 MPa, density within standard limits, water absorption below 20%, and firing shrinkage under 8%. Notably, aluminum content, predominant in the sludge, decreased significantly from 74.17 ppm to 4.97 ppm. These findings suggest that WTS, when integrated into fired bricks, emerges as a viable, cost-effective, and environmentally friendly alternative. The study underscores the potential of utilizing up to 5% WTS in fired clay bricks, presenting a promising avenue for sustainable construction practices.

The interaction between tunnelling and retaining walls represents a complex soil–structure interaction problem that can significantly influence wall deformation and stability. This study investigates and compares the behaviour of cantilever and soil-nailed retaining walls subjected to tunnel excavation beneath the wall in dry Toyoura sand. A series of three-dimensional finite element analyses was performed using an advanced hypoplastic constitutive model to simulate nonlinear sand behaviour and stress-path dependency. Tunnel depth was varied using cover-to-diameter (C/D) ratios of 1.83, 3.33, 4.83, and 6.33. The computed results show that both retaining systems exhibit similar settlement patterns due to tunnelling, with maximum settlement reaching approximately 22.8 mm in the case of C/D = 4.83. However, soil nailing has limited influence on reducing tunnelling-induced settlement. In contrast, the soil-nailed wall develops larger rotation and overturning response due to tensile forces mobilized in the soil nails by tunnelling-induced ground movement. For the shallowest tunnel case (C/D = 1.83), maximum tensile forces reach approximately 72 kN and 60 kN in the top and middle nails, respectively. Tunnelling also causes significant redistribution of contact pressure and shear stress beneath the wall base, including partial loss of contact for shallow tunnels. In addition, lateral earth pressure increases substantially, resulting in total lateral forces up to 3.3 times the pre-tunnelling values. The results demonstrate that tunnel depth governs the wall response, while soil nailing primarily affects rotational behaviour and internal force development rather than settlement mitigation.

The present study was primarily designed to develop a novel composite material composed of peat, limestone, zeolite, and activated carbon (PS-LS-ZE-AC) and to evaluate its simultaneous effectiveness in removing ammoniacal nitrogen (NH₃-N) and chemical oxygen demand (COD) from stabilised landfill leachate. Batch-scale adsorption analyses were performed to identify the optimum compositional ratios, with PS-AC were classified as hydrophobic adsorbents, with the optimum ratio identified as 1.5:2.5. LS-ZE were classified as hydrophilic adsorbents, with the optimum ratio determined as 15:25. The optimal proportion of hydrophobic to hydrophilic adsorbents was determined to be 4:4, as this ratio demonstrated superior adsorption performance for NH₃-N and COD. Characterization of composite was carried out using XRF, FTIR, and SEM. XRF analysis revealed that the main constituents were present in high concentrations of CaO and SiO₂. The composite adsorbents contained several dominant functional groups, notably O–C, C–N, Si–O–Si, O–H, N–H, and C–O. SEM testing demonstrated rough and heterogeneous porous surface of the composite adsorbent. The effects of shaking speed and dosage were examined in conjunction with the reduction of NH₃-N and COD. Fixed-bed columns (FBCs) adsorption experiments indicated reduction efficacy of NH₃-N and COD achieving 99% and 98%. An increase in flowrate resulted in shorter breakthrough and saturation times. The experimental results showed significantly more correlation with the Thomas and Yoon-Nelson compared to Adams-Bohart model. The composite adsorbent was reusable following regeneration with 0.5 M NaCl solution at pH 12, and adjusting using 1 M NaOH, achieving adsorption capacities of NH₃-N and COD 34.13 mg/g and 33.22 mg/g. These findings highlight the efficacy of PS-LS-ZE-AC-based composite adsorbents in treating stabilized landfill leachate.