Bio+mine project: empowering the community to develop a site-specific system for the rehabilitation of a legacy mine

The rehabilitation of legacy mines continues to be a big challenge because of the difficulties in returning them to safe and stable conditions and ensuring that the mined-out areas become productive to support the economic activity of the host community. Previous efforts are often focused on purely technical and environmental aspects, leading to resistance from the local community due to their exclusion from the rehabilitation process. To address the issues associated with legacy mines and lack of participation of the community, we have developed a project, Biodiversity Positive Mining For The Net Zero Challenge (Bio + Mine), focusing on the abandoned Sto. Niño copper mine (Benguet, Philippines). The mine was closed in 1982 without a plan involving local stakeholders and leaving a significant ongoing negative legacy. Using the social-ecological-technological system framework, we will explore the intersections of the structure and functions of socio-economicdemographic, ecological, and technological data useful in devising a more inclusive mitigation strategy for the reconstruction of the supporting ecosystem. We aim to develop a site-specific system, underpinned by the local community's knowledge and practices, that can be a model for wider implementation in other legacy and active mines worldwide

Investigation on mixture design of one-part geopolymer from fly ash and water treatment sludge

This study presents a one-part geopolymer system from coal fly ash and water treatment sludge. Geopolymer is typically produced from two parts namely the aluminosilicate solids, which is typically sourced out from industrial by-product, and an alkali activator solution which reacts with aluminosilicate solids to form an inorganic polymeric network. For a one-part geopolymer system, the solid binder with activators will just be added with water to address the drawback of corrosive and viscous alkali activator solution. Formulation of the proportion of geopolymer precursors with the two solid alkali activators namely sodium hydroxide and sodium aluminate was conducted using statistical mixture design. Effects of each components as well as interactions between them were evaluated by step-wise regression analysis. It was found that high alkali content decreased the compressive strength of binder. Meanwhile, the incorporation of sludge in this system helps reduce the unit weight of samples. Multiple response surface analysis that maximized compressive strength and minimized unit weight resulted in the optimal combination of 18.9% sludge, 76.1% fly ash and 5.0% NaOH

Investigation on mixture design of one-part geopolymer from fly ash and water treatment sludge

This study presents a one-part geopolymer system from coal fly ash and water treatment sludge. Geopolymer is typically produced from two parts namely the aluminosilicate solids, which is typically sourced out from industrial by-product, and an alkali activator solution which reacts with aluminosilicate solids to form an inorganic polymeric network. For a one-part geopolymer system, the solid binder with activators will just be added with water to address the drawback of corrosive and viscous alkali activator solution. Formulation of the proportion of geopolymer precursors with the two solid alkali activators namely sodium hydroxide and sodium aluminate was conducted using statistical mixture design. Effects of each components as well as interactions between them were evaluated by step-wise regression analysis. It was found that high alkali content decreased the compressive strength of binder. Meanwhile, the incorporation of sludge in this system helps reduce the unit weight of samples. Multiple response surface analysis that maximized compressive strength and minimized unit weight resulted in the optimal combination of 18.9% sludge, 76.1% fly ash and 5.0% NaOH

A comparison of the acid mine drainage (AMD) neutralization potential of low grade nickel laterite and other alkaline-generating materials

Acid mine drainage (AMD) is a serious environmental problem caused by the weathering of sulfur-rich minerals found in mine sites, typically pyrite. Passive treatment methods have been extensively studied exploring various materials and treatment systems. Limestone is typically used as neutralizing media through open channels or anoxic limestone drains. However, the armouring that occurs when heavy metals precipitate on the surface restricts the lifespan of limestone treatment systems to 15-20 years. Goethite has been characterized to be a good adsorbent of heavy metals found in wastewater. It is abundant in a layer of nickel laterite deposit which are considered mine wastes due to the low amount of nickel present. This study investigates the performance of locally available nickel laterite ore rock, limestone, fly ash, and cement waste as media for AMD neutralization. The treatment efficiency are evaluated based on the physiochemical properties of the AMD, namely: pH, redox potential (ORP), conductivity, total dissolved solids (TDS), and dissolved oxygen (DO). © 2020 IOP Publishing Ltd

Optimal selection of desalination systems using fuzzy AHP and grey relational analysis

Water scarcity is an alarming global problem for a growing population with depleting sources of fresh water. Desalination is thus becoming an important solution for water management to address such looming shortage of the municipal water supply. At present, several technologies dominate the desalination industry which can be categorized either as a thermal process such as multi-stage flash distillation or a membrane process such as that of reverse osmosis. New desalination systems are also being developed to make the process more cost-effective and energy efficient. Hence, this work proposes a systematic approach for optimal selection of desalination systems using fuzzy analytic hierarchy process (FAHP) and grey relational analysis (GRA). Fuzzy AHP addresses the vagueness involve in the trade-off of the criteria or attributes used in evaluating the alternatives. On the other hand, the GRA solves the multiple criteria decision problem by aggregating the entire range of performance attribute values for every alternative into a single score in spite of incomplete information. An illustrative case study was presented wherein five desalination systems namely reverse osmosis (RO), combined reverse osmosis and forward osmosis (RO-FO), electrodialysis (ED), multi-stage flash distillation (MSF), and combined forward osmosis and membrane distillation (FO-MD) were evaluated. These desalination systems were compared to each other with respect to energy requirement, land footprint, system efficiency, economic viability, and maturity of technology. Sensitivity analysis was also done to determine the robustness of the modeling results from the variation of weights of the criteria. © 2016, AIDIC Servizi S.r.l

Fabrication of polythiourea-copper complex composite membrane and its anti-fouling property

© 2020 IOP Publishing Ltd. A Composite Flat Sheet Membrane Containing Polythiourea-Copper (PTU-Cu) Complex was fabricated through a two-step phase separation involving complexation and/or crosslinking of the polymer by copper ions (Cu2+) on the first step and non-solvent induced phase separation on the second step. The surface topography of the membrane was analysed using Atomic Force Microscope (AFM) in non-contact mode. The incorporation of copper at the surface was confirmed through Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) mapping wherein other elements such as Sulfur (S), Carbon (C) and Oxygen (O) of the polymer were conducted. The fabricated membrane was rigid as shown by high value (about 2.15 GigaPascal) of measured Young\u27s modulus using the Pinpoint Nanomechanical Analysis Mode of AFM. In addition, the surface charge and hydrophobicity were measured using the Electrostatic Force Microscope (EFM) and water contact angle respectively. The antifouling characteristics of the membrane was evaluated through antimicrobial membrane surface contact test wherein E. coli was used as test microorganism. Other membrane properties such as pore size distribution and pure water flux were measured using a porometer and a filtration apparatus

Systems approach toward a greener eco-efficient mineral extraction and sustainable land use management in the Philippines

As the world transition towards a low-carbon future through renewable energy, mining of minerals and metals to attain this goal is substantial. The Philippines will play an important role in such global economy as it is the world’s fifth most mineral-rich country. However, their exploitation has not been maximized to benefit society. Benefits from the mineral resources sector remain less than 2 % of the country’s GDP since 2006, and the mining and mineral processing, including abandoned or legacy mines, are perceived negatively by the public. In low- and middle-income countries with weak implementation of mining and environmental legislation, the mining industry still operates in a linear system which is considered unsustainable. The mining, mineral extraction and processing, and metal extraction are designed to maximize profits with little plan on how to effectively manage mine wastes, protect the environment, transform post-mining land for beneficial use and empower impacted communities. This paper, thus, proposes a systems approach toward greener eco-efficient mineral extraction and sustainable land use management (SAGES). This approach will facilitate a paradigm shift, which is necessary to manage the country’s mineral endowments sustainably without compromising future land use of mining areas while at the same time supporting the needs and aspirations of the impacted host communities. It envisions extending the usability of mining areas beyond the life of the mine and integrating circular economy principles in addressing holistically mine waste management problems. The multi-R framework, originally developed in waste management (Reduce, Reuse, Recycle) and extended to circular economy strategies, has potential applications in mine waste management in the Philippines. An illustrative case study is then presented that employs a multi-R framework to address the mine waste in an operating Ni-laterite mining site

Variation in Dissolved Organic Matter Using Absorbance and Fluorescence Measurements during Dry Season in Sta. Rosa and Cabuyao Rivers, Philippines

Santa Rosa watershed, where the Santa Rosa River and Cabuyao River are located, is growing with increasing urbanization and commercialization in their surroundings. Water quality monitoring is an important tool in understanding the possible impacts of domestic, industrial, and commercial discharges, and agricultural run-off on river systems and their tributaries. With the integration of absorbance and fluorescence measurements, we can further examine the effects of land use and climate change on dissolved organic matter (DOM) sources found in river systems. In this study, these two rivers exhibit poor quality with varying values in each sampling station and period. DOM sources change from terrestrial to endogenous sources within the sampling period. High aromaticity and molecular size were observed in all downstream sampling stations. This is supported by the high values of humic-like substances. Fluorescence index values showed temporal changes from terrestrial to endogenous DOM sources from November 2019 to February 2020. This is also confirmed by the increasing trend in the biological index. The variation in all sampling stations can be attributed to varying land use, hydrological, and climatological changes such as typhoon Tisoy, and Taal Volcano eruption observed during the sampling period

UV-Vis Absorbance and Fluorescence Characterization of Pasig River Surface Water Samples Towards the Development of an LED Fluorescence Lidar System

The status of water quality in Pasig River was studied using UV-Vis absorbance, 3D excitation-emission matrices (EEMs), fluorescence measurements of dissolved organic matter (DOM), and physicochemical parameters measurements. The study was conducted at seven selected sampling stations in Pasig river from April 2019 to June 2019. It has been years since the government has conducted rehabilitation on the Pasig river and we want to determine its current water quality status with the additional information provided by the UV-Vis absorbance and fluorescence spectroscopy. Several surface water samples were collected using the Pasig River ferry system at (St 1) Lawton Station, (St 4) Valenzuela Station, and (St 7) San Joaquin Station. After computing for the absorbance values at 280-nm, 250-nm/365-nm, 253-nm/203-nm, and 226-400, we have used this method to determine the presence of organic carbon and its aromatic substituents. The results showed low humification degree and aromatic structure and vary from April to June 2019. (St 3) shows higher stability organic molecules containing benzene ring structures. A seasonal variability has been observed from the water quality parameters, which is also present from the fluorescence measurements. DOM sources were measured using fluorescence index (FI), the results showed that all surface water samples were terrestrially derived DOM concentrations. The variance can be attributed to the effluents from the land use types near the sampling stations such as industrial and residential waste. Based on the water quality, absorbance and fluorescence results, the impact of marine waters greatly affects the characterization and production of organic materials

Exploring the implementation barriers of eco-toilet system in the Philippines using Decision-Making Trial and Evaluation Laboratory (DEMATEL) approach

© 2020 IOP Publishing Ltd. Eco-Toilet system (ETS) is an emerging sanitation technology that promotes water conservation and nutrient recovery. Although many kinds of literature support the promising benefits of ETS, the implementation of such technology in the Philippines still faces a myriad of challenges. The study found out that the implementation of ETS in the country was affected by the following barriers: (a) policy and institutional capacity/commitment, (b) investment/financial issues, (c) technology and operation viability, and (d) social acceptance. DEMATEL was used as an analytical framework to investigate these key barriers. This method utilized the value judgments of experts and converted this information into quantitative data. Several computations were applied to reveal the causal relationships and prominence of the implementation barriers of ETS in the Philippines. Therefore, this study can benefit decision-makers in addressing implementation issues involving ETS projects in the country