Studi Pemanfaatan Limbah Biomassa sebagai Raw Material Adsorben SiC dalam Penurunan Konsentrasi Amonia sebagai Parameter Bau dalam Air Limbah

ABSTRACT Biomass as raw material is one solution that can be developed in the management of agricultural, plantation, and industrial waste. The utilization of biomass-derived from waste can help reduce pollution and environmental pollution. This research was conducted to make Silicon Carbide (SiC) adsorbent from wood biomass using Sengon sawdust as a source of carbon and non-wood biomass, namely coconut husk, as a source of silica. SiC adsorbent is applied for ammonium adsorption, which has implications on reducing ammonia gas from wastewater, reducing odor. The research methods included isolation of silica and carbon, the production of SiC adsorbent by magnesiothermic reduction, and the characterization of SiC adsorbents with XRD and SEM-EDX. Adsorption capacities of SiC to ammonium were determined according to SiO2:C adsorbent ratios (1:3 and 5:3), adsorbent mass variations, and ammonium concentrations in simulated wastewater using the spectrophotometric method. The results showed that SiC could be used as an adsorbent because there are pores on the surface structure. The optimum SiO2:C adsorbent ratio in adsorbing ammonium was 1:3 (SiC 136) with 45% adsorbed ammonium and an adsorption capacity of 0.47 mg/g. The optimum adsorbent mass in adsorbing ammonium was 0.1 g with 41.77% adsorbed ammonium. The optimum concentration of ammonium in simulated wastewater for ammonium adsorption was 20 mg/L with 46.25% adsorbed ammonium. The adsorption isotherm pattern during the ammonium adsorption process follows the Freundlich isotherm, which means that the adsorption process occurs physically. Keywords: adsorbent, adsorption, ammonia, biomass, coconut husk, SiC ABSTRAK Biomassa sebagai raw material merupakan salah satu solusi yang dapat dikembangkan dalam pengelolaan limbah hasil pertanian, perkebunan, dan industri. Pemanfaatan biomassa yang berasal dari limbah dapat membantu mengurangi tingkat polusi dan pencemaran lingkungan. Penelitian ini dilakukan untuk membuat adsorben Silikon Carbida (SiC) dari biomassa kayu yaitu memanfaatkan serbuk gergaji kayu Sengon sebagai sumber karbon dan biomassa non kayu yaitu sabut kelapa sebagai sumber silika. Adsorben SiC diaplikasikan dalam penjerapan amonium yang berimplikasi pada potensi penurunan gas amonia dari air limbah sehingga adsorben SiC berpotensi mengurangi bau dalam air limbah. Metode penelitian meliputi isolasi silika, isolasi karbon, pembuatan adsorben SiC secara reduksi magnesiotermik dan karakterisasi adsorben SiC dengan XRD dan SEM-EDX. Penentuan daya adsorpsi SiC sebagai adsorben terhadap variasi rasio adsorben SiO2:C (1:3 dan 5:3), variasi massa adsorben, variasi konsentrasi limbah simulasi menggunakan metode spektrofotometri. Hasil penelitian menunjukkan bahwa SiC dapat digunakan sebagai adsorben karena terdapat pori-pori pada struktur permukaan. Variasi rasio adsorben SiO2:C optimum dalam mengadsorpsi amonium ialah SiC 136 dengan amonium teradsorpsi sebanyak 45% dan kapasitas adsorpsi sebesar 0,47 mg/g. Massa adsorben optimum dalam mengadsorpsi amonium ialah 0,1 g dengan amonium teradsorpsi 41,77%. Konsentrasi optimum limbah simulasi dalam adsorpsi amonium 20 mg/L dengan amonium teradsorpsi 46,25%. Pola isoterm adsorpsi selama proses adsorpsi amonium mengikuti isoterm Freundlich, yang berarti proses adsorpsi cenderung terjadi secara fisika. Kata kunci: adsorben, adsorpsi, amonia, biomassa, sabut kelapa, SiC

Ammonium Release and Adsorption Characters of Polyurethane–Biochar Crosslinked Material as an Additive Filler in Stormwater Treatment

The additive fillers in bioretention facilities play a leading role in stormwater treatment to purify polluted runoff. At present, many traditional materials could not meet the requirements at the same time, including low ammonium leaching quantities, high water storage volume and strong ammonium adsorption. This study investigated a polymer material, polyurethane–biochar crosslinked material (PCB), to evaluate the feasibility of using it as an additive filler in stormwater treatment compared with its raw material hardwood biochar (HB), and two traditional fillers. Successive leaching and ammonium isothermal adsorption experiments were conducted in deionized water and artificial stormwater. PCB leached 4.98–5.31 μmol/g NH4-N, less than the leaching quantities of compost, the traditional filler. After polyurethane modification, ammonium adsorption of PCB was improved: at a typical ammonium concentration of 2 mg/L in stormwater, PCB could adsorb 43.6 mg/kg ammonium versus 34.6 mg/kg for HB. With the addition of PCB in sand column, the ammonium adsorption improved from 31.34 to 84.72%. To improve the performance of bioretention facilities, PCB is recommended to be added into filter layers in stormwater treatment, taking advantage of its high cation exchange capacity and spongy internal structure to minimize overland flooding and enhance removal of ammonium from stormwater.

Process-based models for nitrogen dynamics in subsurface flow constructed wetlands: A state-of-the-art review

In the last two decades, several process-based models had been developed to describe the transport and fate of contaminants in subsurface flow constructed wetlands (SSF CWs) under a variety of conditions. These models have become valuable tools to better design, control and optimize the SSF CW system. Moreover, they can aid investigations on the effects of variables of interest on the system. While excellent review papers on these models have been published, the ability of the existing process-based models in simulating the nitrogen transformations in the SSF CWs have not been highlighted. Consequently, a critical review of the simulation of nitrogen transformation processes is desirable. This paper presents an overview of the available models which are capable of modelling the nitrogen dynamics in the SSF CWs. The existing process-based models can be mainly categorized as the process-dedicated models and Gujer matrix models. A process-dedicated model is a feasible tool for design purposes. Meanwhile, the Gujer matrix model delivers valuable insights into scientific studies. In this paper, the existing models are summarized and critically discussed with regards to their capability and practicality in simulating the nitrogen dynamics in SSF CWs. Organic nitrogen, ammonium, and nitrate are the common nitrogen compounds considered in the process-based models of SSF CWs. Meanwhile, nitrite was frequently considered together with nitrate due to its low concentration in the effluent of SSF CWs. On the other hand, ammonification, nitrification, denitrification, plant uptake and ammonium adsorption are the typical nitrogen transformation and degradation processes found in the existing models, whilst ammonia volatilization was rarely found in the literature. Oxygen and organic matter are the major limiting reactants of nitrogen transformation and degradation processes in the modelling, and other factors such as microbial population, temperature and pH are also considered. The recommendations and future research directions on the influence of microorganism distribution, resting period, oxygen release, ammonium adsorption and plants are outlined.