Investigation of the accumulation of strategic raw materials magnesium (Mg) and phosphorus (P) from various wastewater streams using macroalgae (Cladophora fracta)

Abstract

Context—Mining and processing activities for obtaining strategic raw materials bring with them many difficult problems to overcome, such as the destruction of natural areas, disruption of ecosystems, waste generation, and environmental pollution. Among these raw materials, magnesium (Mg) and phosphorus (P) have become the focus of more attention in recent years due to their widespread use in various industrial sectors and technological applications, and their essential role for the human body. When these strategic raw materials reach water bodies, phosphorus load increases, leading to environmental and economic impacts. Furthermore, high levels of Mg in wastewater discharges cause persistent hardness in water and various problems in water treatment.

Objective—Phycoremediation is a treatment technique that involves the use of algae as a viable and cost-effective solution in wastewater treatment.  This technique also stands out for its ability to produce algal biomass with high recovery potential and that can be easily converted into valuable products. This technique using algae may be an effective solution for the accumulation of strategic raw materials from wastewater environments.  In this study, the macroalgae Cladophora fracta (C. fracta) was used for the accumulation of Mg and P from wastewater.

Method—C. fracta collected from its natural habitat was exposed to domestic wastewater, industrial wastewater, and landfill leachate and harvested daily. The harvested algae were dried and ground in a grinder. Mg and P concentrations in the powdered samples were determined using ICP-MS. Daily accumulations were calculated from the initial and final concentrations, and the harvesting periods (the day with the highest accumulation) for Mg and P in C. fracta were determined.

Results—The highest Mg accumulation in C. fracta was ranked as follows: Domestic wastewater > Landfill leachate > Industrial wastewater, while the highest P accumulation was ranked as follows: Industrial wastewater > Domestic wastewater > Landfill leachate. In domestic and industrial wastewater, the highest accumulation was P > Mg, while in landfill leachate, the highest accumulation was Mg > P. As a result, Mg and P were accumulated in wastewater at high rates of 71.2 ± 3.6% and 783 ± 39.2% using C. fracta.

Conclusion—In this study, it was demonstrated that the accumulation process using C. fracta may be effective in minimizing or eliminating the environmental risks caused by Mg and P. The accumulation of strategic raw materials found in wastewater offers an extremely advantageous opportunity in terms of preventing these materials from dispersing and being lost through wastewater flows and preserving natural resources. Future studies could investigate techniques for recovering these strategic raw materials from algal biomass and their economic viability.

Keywords

• Accumulation
• Industrial wastewater
• Domestic wastewater
• Phycoremediation
• Landfill leachate
• Strategic raw materials

Stratejik hammaddelerden magnezyum (Mg) ve fosfor (P)’un çeşitli atıksulardan makroalg (Cladophora fracta) ile akümülasyonunun araştırılması

Abstract

Arka Plan—Stratejik hammaddelerin elde edilmesi için maden çıkarma ve işleme gibi faaliyetler doğal alanların tahribi, ekosistemin bozulması, atık oluşumu ve çevre kirlilikleri gibi üstesinden gelinmesi zor olan birçok sorunu da beraberinde getirmektedir. Bu hammaddelerden magnezyum (Mg) ve fosfor (P) çeşitli endüstriyel sektörler ile teknolojik uygulamalarda yaygın kullanımları ve insan vücudu için temel element olmaları nedeniyle son yıllarda daha fazla ilgi odağı haline gelmiştir. Bu stratejik hammaddelerden P, söz konusu su kütlelerine ulaştıklarında P yükünün artmasına ve bunun bir sonucu olarak çevresel ve ekonomik etkilere yol açmaktadır. Ayrıca, atıksu deşarjlarındaki yüksek Mg seviyeleri ise suda kalıcı sertliğe ve su arıtımında çeşitli sorunlara neden olmaktadır.

Amaç—Fikoremediasyon, atıksu arıtımında uygun ve ucuz bir çözüm olarak alglerin kullanımını içeren bir arıtım tekniğidir. Bu teknik aynı zamanda geri kazanım potansiyeli yüksek ve nitelikli ürünlere kolayca dönüştürülebilen alg biyokütlesi elde edebilme özellikleri ile ön plana çıkmaktadır. Alglerin kullanıldığı bu teknik atıksu ortamlarından stratejik hammaddelerin akümülasyonunda etkili bir çözüm olabilir. Bu amaçla bu çalışmada, atıksulardan Mg ve P’un akümülasyonu için makroalg Cladophora fracta (C. fracta) kullanılmıştır.

Method— Doğal ortamından toplanan C. fracta evsel atıksu, endüstriyel atıksu ve çöp sızıntı suyuna maruz bırakılmış ve günlük olarak hasatlanmıştır. Hasatlanan algler kurutulmuş ve bir öğütücüde öğütülmüştür. Partikül boyutı azaltılarak homojen hale getirilen örneklerdeki Mg ve P konsantrasyonları ICP-MS kullanılarak tespit edilmiştir. İlk ve son konsantrasyonlardan günlük akümülasyonlar hesaplanmış ve Mg ve P için C. fracta’nın hasatlama süreleri (akümülasyonun en yüksek olduğu gün) belirlenmiştir.

Bulgular—C. fracta’da elde edilen en yüksek Mg akümülasyonu, Evsel atıksu > Sızıntı suyu > Endüstriyel atıksu şeklinde, en yüksek P akümülasyonu ise Endüstriyel atıksu > Evsel atıksu > Sızıntı suyu şeklinde sıralanmıştır. Evsel atıksu ve endüstriyel atıksuda en yüksek akümülasyon P > Mg olarak, sızıntı suyunda ise en yüksek akümülasyon Mg > P olarak sıralanmıştır. Sonuç olarak Mg ve P, C. fracta kullanılarak atıksulardan Mg için %71.2 ± 3.6, P için %783 ± 39.2 gibi yüksek oranlarda akümüle edilmiştir.

Sonuç—Bu çalışmada Mg ve P’un sebep olacağı çevresel risklerinin en aza indirilmesi veya ortadan kaldırılmasında C. fracta kullanılarak gerçekleştirilen akümülasyon ile mümkün olabileceği gösterilmiştir. Atıksularda bulunan stratejik hammaddelerin akümülasyonu bu hammaddelerin atıksu akışlarıyla dağılıp kaybolmaması ve doğal kaynakların korunması açısından son derece iyi bir avantaj sunmaktadır. Gelecekteki çalışmalarda alg biyokütlesinden bu stratejik hammaddelerin geri kazanımı teknikleri ve ekonomik kazanımı araştırılabilir.

Keywords

• Akümülasyon
• Endüstriyel atıksular
• Evsel atıksular
• Fikoremediasyon
• Sızıntı suları
• Stratejik hammaddeler

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