Strategi Pemanfaatan Limbah Slag Aluminium Menjadi Geopolimer secara Berkelanjutan di Kabupaten Jombang

Abstract

Peleburan limbah aluminium di Kabupaten Jombang sudah berlangsung sejak tahun 1976. Kegiatan tersebut melibatkan masyarakat sekitar dalam bentuk usaha mikro, kecil, dan menengah (UMKM). Kecamatan Sumobito, Kabupaten Jombang dipilih karena memiliki paling banyak UMKM ilegal, masif, dan kondisi pencemaran lingkungan yang terjadi dimana-mana. Kegiatan tersebut memberikan dampak positif berupa peningkatan ekonomi secara langsung untuk UMKM dan secara tidak langsung terhadap masyarakat di sekitar. Kegiatan tersebut memiliki dampak negatif, karena menghasilkan limbah berupa limbah slag aluminium yang dibuang ke lingkungan. Permasalahan menjadi kompleks karena melibatkan aspek lingkungan, ekonomi, sosial kelembagaan, dan teknologi.

Limbah slag aluminium menurut Peraturan Pemerintah (PP) No. 22 tahun 2021 tentang 2021 tentang Penyelenggaraan Perlindungan dan Pengelolaan Lingkungan Hidup termasuk kategori limbah bahan berbahaya dan beracun (limbah B3). Limbah B3 berpotensi menyebabkan pencemaran lingkungan dan gangguan kesehatan terhadap masyarakat. Limbah slag aluminium yang dibuang ke lingkungan dapat menyebabkan pencemaran terhadap tanah, air, dan udara. Pengelolaan limbah B3 wajib sesuai dengan aturan dan harus dilakukan oleh pihak ketiga yang memiliki izin pemanfaatan atau pengolahan limbah B3.

Limbah slag aluminium merupakan campuran kompleks yang terdiri atas garam, oksida logam, dan senyawa lainnya. Limbah slag aluminium didominasi oleh alumina dengan jumlah lebih dari 70%. Hal tersebut menjadi peluang untuk dimanfaatkan sebagai sumber bahan baku alumina. Beberapa penelitian telah dilakukan terkait pemanfaatan limbah slag aluminium, salah satunya yaitu menjadi geopolimer. Geopolimer adalah aluminasilika anorganik yang dapat disentesis dari material yang mengandung silika dan alumina yang berasal dari alam atau dari limbah. Geopolimer dipilih karena proses yang relatif sederhana, tidak menghasilkan limbah baru, dan ramah lingkungan. Pemanfaatan slag aluminium menjadi geopolimer diharapkan dapat mengurangi potensi pencemaran lingkungan yang terjadi di Kecamatan Sumobito, Kabupaten Jombang.

Tujuan utama penelitian ini adalah merumuskan strategi pemanfaatan limbah slag aluminium menjadi geopolimer secara berkelanjutan di Kabupaten Jombang. Tujuan antara diperlukan untuk mencapai tujuan utama di antaranya yaitu menganalisis kondisi sosial kelembagaan terkait kegiatan peleburan limbah aluminium, menganalisis kondisi lingkungan terkait kegiatan peleburan limbah aluminium, menyintesis limbah slag aluminium menjadi geopolimer, dan menganalisis kelayakan ekonomi kegiatan pemanfaatan limbah slag aluminium menjadi geopolimer. Kebaruan dari penelitian ini yaitu: (1) menentukan status pencemaran di Kecamatan Sumobito, Kabupaten Jombang karena kegiatan pembuangan limbah slag aluminium ke lingkungan; (2) menyintesis geopolimer dari limbah slag aluminium di Kabupaten Jombang; dan (3) strategi pemanfaatan limbah slag menjadi geopolimer di Kabupaten Jombang secara berkelanjutan.

Kondisi existing terkait kegiatan peleburan limbah aluminium diketahui melalui analisis sosial kelembagaan dan analisis kondisi lingkungan. Kondisi sosial kelembagaan dilakukan dengan metode analisis deskriptif kualitatif melalui data hasil observasi lapang, kuisioner, dan wawancara. Hasil yang diperoleh berupa rantai pasok limbah aluminium, tahapan proses peleburan limbah aluminium, peran para pihak, dan persepsi masyarakat terkait dengan kegiatan peleburan limbah aluminium di Kabupaten Jombang. Kondisi lingkungan diketahui melalui uji kualitas air dan tanah. Hasil pengujian air permukaan yaitu dua sungai dan air irigasi di lokasi kegiatan terindikasi cemar ringan. Air bersih dari sumur warga terindikasi cemar ringan. Hasil analisis logam berat pada tanah terkontaminasi yaitu semua sampel area dumping ilegal dan satu sampel tanah (Desa Kendalsari) harus dikelola sebagai limbah B3. Tiga sampel tanah lainnya dikelola sebagai limbah non B3. Tingginya kadar logam berat pada tanah disebabkan karena adanya infiltrasi logam berat dari area dumping ilegal ke area tanah di sekitar.

Sintesis slag aluminium menjadi geopolimer dilakukan melalui karakterisasi slag aluminium, sintesis dan karakterisasi geopolimer. Limbah slag aluminium memiliki karakteristik bahaya karena mudah bereaksi dengan air menghasilkan 115,5 mL gas/ 0,5 g slag aluminium. Gas teridentifikasi sebagai hidrogen, metana, dan amonia yang bersifat berbahaya. Geopolimer berhasil disintesis dari limbah slag aluminium dengan berbagai variasi uji. Geopolimer diuji pelindian (leaching) dan mampu menurunkan leaching Pb dibandingkan slag aluminium, yang diharapkan aman bagi lingkungan. Karakterisasi dilakukan dengan Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Gas Chromatography-Thermal Conductivity Detector (GC-TCD), Scanning Electron Microscopy (SEM), dan Atomic Absorption Spectroscopy (AAS).

Pemanfaatan slag aluminium menjadi geopolimer dikaji kelayakannya melalui analisis biaya manfaat atau cost benefit analysis (CBA). Hasil analisis ekonomi mendapatkan benefit cost ratio (BCR) sebesar 3,96 dan internal rate of return (IRR) 27%. Hal tersebut menyimpulkan bahwa kegiatan pemanfaatan limbah slag aluminium menjadi geopolimer layak secara ekonomi.

Tujuan utama dirumuskan melalui soft system methodology Checkland. Transformasi dapat dilakukan melalui tindakan aksi perbaikan yaitu: (1) merancang pemanfaatan slag aluminium menjadi geopolimer; (2) peningkatan kualitas dan kuantitas SDM; (3) inovasi produk; (4) merekomendasikan strategi kepada otoritas terkait; (5) penerbitan kebijakan; dan (6) monitoring dan evaluasi. Transformasi slag aluminium menjadi geopolimer diharapkan menjadi solusi permasalahan yang ada di Kabupaten Jombang terkait dengan pencemaran lingkungan karena limbah slag aluminium. Rekomendasi dan model implementasi menjadi referensi otoritas terkait untuk menyusun kebijakan yang adil bagi lingkungan maupun masyarakat.

Aluminum waste recycling activities in Jombang Regency have been ongoing since 1976. These activities involve the local community through micro, small, and medium enterprises (MSMEs). Sumobito Subdistrict in Jombang Regency was selected as the focus area due to the high concentration of illegal and large-scale MSMEs, along with widespread environmental pollution. While these activities have had positive impacts such as direct economic benefits for MSMEs and indirect benefits for the surrounding community they have also generated significant negative impacts. One of the main issues is the production of aluminum slag waste, which is often disposed of directly into the environment. This problem has become complex, as it encompasses environmental, economic, socio-institutional, and technological aspects.

According to Government Regulation No. 22 of 2021 concerning the Implementation of Environmental Protection and Management, aluminum slag waste is classified as hazardous waste. Such waste poses significant risks to both the environment and public health, with the potential to contaminate soil, water, and air when improperly disposed of. The management of hazardous waste must adhere to applicable regulatory frameworks and be undertaken by licensed third-party entities authorized for the utilization or treatment of hazardous waste.

Aluminum slag waste is a heterogeneous mixture composed primarily of salts, metal oxides, and other inorganic compounds. It is predominantly composed of alumina (Al2O3), which constitutes more than 70% of its total composition, thereby presenting a potential opportunity for its utilization as a secondary source of alumina. Numerous studies have investigated the processing and valorization of aluminum slag waste, one of which involves its application in the synthesis of geopolymers. Geopolymers are inorganic aluminosilicate materials that can be synthesized from alumina- and silica-rich substances, including natural minerals and various forms of waste. Geopolymers are considered a sustainable alternative due to their relatively simple production process, minimal generation of secondary waste, and environmentally friendly characteristics. The conversion of aluminum slag waste into geopolymer materials is expected to mitigate the risk of environmental pollution, particularly in Sumobito Subdistrict, Jombang Regency.

The primary objective of this study is to formulate a sustainable strategy for the utilization of aluminum slag waste as a geopolymer in Jombang Regency. Several intermediate objectives are required to achieve this main goal, including: (1) analyzing the socio-institutional conditions related to aluminum waste recycling activities; (2) assessing the environmental conditions associated with these activities; (3) synthesizing aluminum slag waste into geopolymers; and (4) evaluating the economic feasibility of utilizing aluminum slag waste as a geopolymer. The novelty of this research lies in three key contributions: (1) determining the pollution status in Sumobito Subdistrict, Jombang Regency resulting from the disposal of aluminum slag waste into the environment; (2) synthesizing geopolymer materials from locally sourced aluminum slag waste; and (3) developing a sustainable strategy for utilizing aluminum slag waste as a geopolymer in Jombang Regency.

The existing conditions aluminum waste recycling activities were identified through a socio-institutional and an assessment of environmental analysis. The socio-institutional analysis was conducted using a qualitative descriptive method based on data obtained from field observations, questionnaires, and interviews. The results include the aluminum waste supply chain, the recycling process, stakeholder roles, and community perceptions regarding aluminum smelting activities. The environmental assessment was conducted through water and soil quality testing. The surface water test results covering two rivers and irrigation water indicated a slight level of pollution. Clean water from community wells was found slight contamination. Heavy metal analysis, compared against the total concentration of pollutants in contaminated soils, revealed that all aluminum slag waste pile samples and one soil sample must be managed as hazardous waste. The remaining three soil samples were categorized as non-hazardous waste. The elevated concentrations of heavy metals in the soil are attributed to the infiltration of metals from waste piles into the surrounding soil areas.

The synthesis of aluminum slag into geopolymers was conducted through aluminum slag characterization, geopolymer synthesis, and characterization. Aluminum slag is classified as hazardous due to its high reactivity with water, which generates 115,5 mL of gas per 0,5 grams of slag. The gases identified as hydrogen, methane, and ammonia, all of which are hazardous in nature. Geopolymers were successfully synthesized from aluminum slag using various experimental. Leaching tests demonstrated that the geopolymer reduced lead (Pb) leaching compared to aluminum slag, indicating its potential environmental safety. The synthesized geopolymer was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Gas Chromatography–Thermal Conductivity Detector (GC-TCD), Scanning Electron Microscopy (SEM), and Atomic Absorption Spectroscopy (AAS).

The feasibility of utilizing aluminum slag as a geopolymer was evaluated through a Cost-Benefit Analysis (CBA). The economic analysis yielded a benefit cost ratio (BCR) ratio of 3,96 and an internal rate of return (IRR) of 27%. These results indicate that the utilization of aluminum slag waste for geopolymer production is economically feasible.

The main objective was formulated using Soft Systems Methodology Checkland. The transformation can be achieved through a series of corrective actions, including: (1) designing the utilization of aluminum slag into geopolymers; (2) improving the quality and quantity of human resources; (3) fostering product innovation; (4) recommending strategic actions to relevant authorities; (5) issuing appropriate policies; and (6) implementing monitoring and evaluation mechanisms. The transformation of aluminum slag into geopolymers is expected to offer a viable solution to the environmental pollution issues associated with aluminum slag waste in Jombang Regency. The proposed recommendations and implementation model are intended to serve as a reference for relevant authorities in formulating policies that are both environmentally and socially equitable.