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ALTERNATIF PENANGANAN

AIR ASAM TAMBANG (AAT)

Jon Hendri, SP., M.Si

Dr. Diyah Tjahyandari

BALAI PENGKAJIAN TEKNOLOGI PERTANIAN JAMBI

2016

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KONDISI AAT DILAPANGAN

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AIR ASAM TAMBANG (AAT)

•Di mana AAT timbul/menjadi masalah?

Pertambangan batubara, logam-logam: emas, perak,tembaga, seng, mangan, dan timbal

•Apa masalah yang ditimbulkannya?

pembentukan keasaman (acid generation) danpelarutan logam-logam (metals dissolution)

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BAGAIMANA AAT DAPAT TIMBUL?

•2FeS2 (s) + 7O2 (aq) + 2H2O –> 2Fe+2 + 4SO4-2 + 4H+ (1)

•2Fe+2+ ½ O2 + 2H+ –> 2Fe+3 + H2O (2)

•2Fe+3 + 6H2O <–> 2Fe(OH)3 (s) + 6H + (3)

•14Fe+3 + FeS2 (s) + 8H2O –> 2SO4-2 + 15Fe+2 + 16H + (4)

•Thiobacillus Ferroxidans

•Ferroplasma Acidarmanus

ION H+ DENGAN BEBERAPA LOGAM MEMBENTUK ENDAPAN

•Al+3 + 3H2O <–> Al(OH)3 + 3H+ (5)

•Fe+3 + 3H2O <–> Fe(OH)3 + 3H + (pers.3) (6)

•Fe+2 + 0.25 O2 (aq) + 2.5 H2O <–> Fe(OH) 3 + 2H + (7)

•Mn+2 + 0.25 O2 (aq) + 2.5 H2O <–> Mn(OH) 3 + 2H + (8)

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•Sphalerite ZnS(s) + 2O2(aq) –> Zn+2 + SO4-2 (9)

•Galena PbS(s) + 2O2 (aq) –> Pb+2 + SO4-2 (10)

•Millerite NiS(s) + 2O2 (aq) –> Ni+2 + SO4-2 (11)

•Greenockite CdS(s) + 2O2 (aq) –> Cd+2 + SO4-2 (12)

•Covellite CuS(s) + 2O2 (aq) –> Cu+2 + SO4-2 (13)

•Chalcopyrite CuFeS2(s) + 4O2 (aq) –> Cu+2 + Fe+2 + SO4-2 (14)

Definisi air asam tambang (AAT) (lanjutan)

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KARAKTERISTIK “MINE WASTE”

•Sifat fisik: persentase rock fragmen, tekstur, bulk density, porositas, kemampuan mengikat air rendah campuran bahan/material geologi yang beragam

•Sifat kimia: C orgnik, N total rendahdengan KTK rendah

•Walaupun secara mineralogi sifat minewaste mirip dengan sifat tanah disekitarnya, tetapi perlakuan terhadapmine waste harus hati-hati

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ALTERNATIF CARA PENANGGULANGAN AAT

• If the goal or outcome is to reduce toxicity or to recover metals then it would probably be considered an innovative treatment; if the goal is to prevent metals contaminated soils from being blown into nearby yards, but the metals are still present in the same quantities it would probably be considered traditional.

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LANJUTAN…..

• Pendekatan untuk menangani solid mine wastes: ekskavasi, landscape adjustment, dan teknik stabilisasi. Tujuan untuk menghindari infiltrasiair ke dalam solid wastes, dengan cara menutupi mine waste denganbahan-bahan: clay or plastic caps, etc. plastic, cement, soil, compost, rock, vegetation, etc. agar tidak terekspos sehingga tidak menimbulkanmasalah. Solusi ini tidak mengurangi toksisitas atau volume logamdalam mine waste.

• Mine waste juga dapat dishipped off-site to landfills, treatment plants, or recovery operations, akan tetapi solusi ini lebih mahal

• Re-grading: mengurangi slope waste rock atau tailing pile untukmencegah erosi, mengurangi runoff dan menyediakan permukaan yang lebih stabil untuk revegetatsi.

• Aliran air juga dapat dikontrol dengan membagi aliran dari pile denganpembuatan teras dan culvert.

• Penggunaan biosolid dan kapur untuk establishing self-sufficient vegetative cover.

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• Kimia (Active treatment)

Kalsium (calcium carbonate). Kandungan kalsium padalimestone sebaiknya cukup tinggi (Dolomitic limestones kurangreaktif dibandingkan limestone, shg kurang efektif untuk AAT),efektif untuk acidity kurang dari 50 mg/l.

• CaCO3 + 2H+ = Ca+2 + H2O + CO2 (15)

• CaCO3 + H2CO3 = Ca+2 + 2HCO3 (16)

Kelebihannya: relatif murah, mudah aplikasinya, penanganansludge yg terbentuk oxyhyroxides (FeOOH) or hydroxides (Fe(OH)relatif lebih mudah dan murah (dibandingkan dengan bahan lain)

Kekurangannya: reaksi lambat, efisiensi cepat menurun karenacoating endapan besi pada permukaan partikel limestone,sulit/tidak efektif pada tambang yg memiliki rasio ferrous-ferrictinggi , tidak efektif menghilangkan mangan.

LANJUTAN…..

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• Hydrated lime (calcium hydroxide) umum digunakandi pertambangan batubara

• Kelebihannya: mudah, aman, relatif murah, efkctif

• Kekurangannya: pembentukan voluminous sludge(lebih banyak bila dibandingkan dengan limestone),dan biaya yang tinggi untuk menanggulangi sludge

• Soda Ash (sodium carbonate)

Kelebihannya: efektif untuk aliran AAT yang kecil

Kekurangannya: mahal (dibandingkan limestone dan adanya pembentukan sludge.

LANJUTAN…..

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• Ammonia (Anhydrous ammonia)

• Kelebihannya: efektif untuk AAT yang memiliki kandungan besi ferousdan atau mangan yang tinggi, harga lebih murah daripada causticsoda.

• Kekurangannya: sulit penggunaannya, berbahaya, mempengaruhikondisi biologi daerah sekitar pertambangan, beracun bagi ikan danpenghuni air lainnya (ikan memiliki toleransi yg rendah terhadapammonia yg tidak terionisasi) and toxicity levels can be affected by pH,temperature, dissolved oxygen and other factors. , menimbulkaneutrophication dan nitrifikasi. A more complete review of ammoniatreatment of mine drainage is given by Faulkner (1991). Ammonia useis not allowed in all States and, where permitted, additional monitoringis required.

LANJUTAN…..

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BIOLOGI (PASSIVE TREATMENT)

Pembuatan Wetland: menggunakan soil- and water-borne mikroba(SRB: sulfat reducing bacteria) yang berasosiasi dengan tanamanwetland untuk menghilangkan logam-logam terlarut.

-SO42- + 2CH2O —> H2S + 2HCO3 (17)

H2S + M+2 —> MS + 2H+

Kelebihannya: biaya pemeliharaan rendah dan tidak memerlukanperlakuan terus menerus. Umumnya lebih efektif untuk menanganimangan daripada besi

Kekurangannya: desain dan pembuatan wetland di awal mahal (berkisarpuluhan ribu dollar). Karena merupakan penemuan relatif baru, makabanyak hal yang belum difahami, seperti optimal ukuran wetland, kriteriakonfigurasi, variasi musiman penghilangan logam-logam terutama di lokasi yang memiliki iklim dingin.

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WETLAND ARTIFICIAL

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WETLAND ARTIFICIAL

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PEMANFAATAN TANAMAN AIR MENGURANGI LOGAM BERAT

MAU DIAPAKAN LAHAN PASCA TAMBANG

DI JAMBI????

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TERIMA KASIH BLAMBUN

Alternatif cara penanggulangan AAT (lanjutan)

• Permeable Reactive Barriers (PRBs): barriers yang bereaksidengan spesifik unsur2 kimia, ditempatkan di jalur aliran airtanah yang memungkinkan air mengalir dengan mudah(Blowes et. al, 2000).

• Pada PRBs yang didesain untuk menangani AAT dengankandungan logam, maka barrier umumnya terdiri dari bahanorganik padat, kompos daun, dan wood chips/sawdust(Blowes, et. al., 2000). Bahan organik mempercepatproliferation bakteri pereduksi sulfat untuk mereduksi sulfatmenjadi sulfida

Alternatif cara penanggulangan AAT (lanjutan)

• Biosolids are treated municipal sewage sludge;

• EPA defines biosolids as follows: “...the nutrient-rich organic materialsresulting from the treatment of sewage sludge (the name for the solid,semisolid or liquid untreated residue generated during the treatment ofdomestic sewage in a treatment facility). When treated and processed,sewage sludge becomes biosolids which can be safely recycled and appliedas fertilizer to sustainably improve and maintain productive soils andstimulate plant growth.”

• Biosolids have a growing number of useful applications and the search formore continues as population and hence sludge production increases.

• Biosolids are being used to reclaim mine lands (Murray et al., 1981; Sopper,1993; Toffey, 2003) and have also been used for agricultural purposes.

• Dikombinasikan dengan kapur

Alternatif cara penanggulangan AAT (lanjutan)

• Phytoremediation suggests the use of plants to treat orremove contamination (phytoextraction/phtyomining,phytostabilization, rhizofiltration, and phytovolatilization).

• EPA: “the uptake of contaminants by plant roots andtranslocation within the plants. This concentrationtechnology leaves a much smaller mass to be disposed ofthan does excavation of the soil or other media”

• Wong defines the term as, “the use of green plants andtheir associated microbiota, soil amendments, andagronomic techniques to remove, contain, or renderharmless environmental contaminants (2003).

Alternatif cara penanggulangan AAT (lanjutan)

• Phytostabilization is to prevent soil erosion and deposition of contaminated soils in streamsand nearby lands. The EPA defines it as:

• “(1) immobilization of a contaminant in soil through adsorption and accumulation by roots,adsorption onto roots, or precipitation within the root zone of plants, and

• (2) the use of plants and plant roots to prevent contaminant migration via wind and watererosion, leaching, and soil dispersion”

• Ideal plants for this technique use metal-tolerant, drought-resistant, fast growing crops thatcan also grow in nutrient deficient soils (Wong, 2003).

• Kelebihannya: a relatively inexpensive technique, soils do not need to be removed, ecosystemrestoration is enhanced, and disposal of hazardous materials or biomass is not required .

• Kekurangannya: the contaminants remain in place - care must be taken to ensure that thevegetation continues to stabilize the metals; extensive fertilization or soil modification may benecessary; plant uptake and translocation of metals must be prevented; root zones, rootexudates, contaminants, and soil amendments must be monitored to prevent an increase inmetal solubility and leaching; it may only be considered a temporary measure; stabilizationmight be due primarily to the effects of soil amendments, with plants only contributing tostabilization by decreasing the amount of water moving through the soil and by physicallystabilizing the soil against erosion

• The application of biosolids fits well with this phytoremediation technique as it providesnecessary fertilizing agents and aids in microorganism establishment.

Alternatif cara penanggulangan AAT (lanjutan)• Phytovolatilization has been identified as a potential treatment for

mercury and selenium contaminated soils (Chaney, et al., 1997; EPA,2000).

• Phytovolatilization is defined by the EPA as, “...uptake and transpirationof a contaminant by plant, with release of the contaminant or amodified form of the contaminant to the atmosphere from the plantthrough contaminant uptake, plant metabolism, and planttransportation” (EPA, 2000).

• This process is beneficial if the contaminants of concern will betransformed to less-toxic forms, for example elemental mercury anddimethyl selenite gas.

• Kekurangannya: metabolites, unhealthy plant accumulation, anduncertainty about other constituents at the site, i.e., where there is oneform of contamination there could be many more and one mustunderstand how they will react with the plants as well.