Judul: Pemanfaatan limbah tahu sebagai sumber nitrogen pupuk organik
Abstrak: Limbah dari industri tahu relatif besar, apabila tidak diolah dan dimanfaatkan secara memadai dapat mencemari lingkungan dan merupakan pembuangan protein besar-besaran. Penelitian ini dilakukan dalam rangka memanfaatkan limbah tahu sebagai sumber nitrogen organik yang murah khususnya untuk pupuk organik. Protein sebagai sumber nitrogen organik diekstraksi dari limbah padat tahu dalam KOH IN. Ekstrak limbah padat tahu selanjutnya digunakan untuk mengekstrak bahan pupuk organik. Kadar N, P, dan K pupuk organik yang diperoleh berturut-turut adalah 0,213%, 0,038%, 1,05%. Pupuk organik yang diperoleh kemudian diuji cobakan pada tanaman tauge yang hasilnya kemudian dibandingkan terhadap tanaman tauge yang hanya diberi air. Hasilnya menunjukkan bahwa tanaman tauge yang diberi pupuk pertumbuhannya lebih cepat.
Keyword: 

Judul: Kualitas Pupuk Organik Cair dari Campuran Limbah Cair Tahu dan Kotoran Sapi.
Abstrak: Tofu waste water containing organic material out of complex as well as carbon and N is high. This will reduce the level of water quality and ultimately have a negative impact on aquatic ecosystems. Liquid tofu waste have a great potential to used as liquid organic fertilizer due to the nutrition contents that needed by plants. The objective of this research was to evaluate the quality of liquid fertilizer from liquid tofu waste. In this research use different ratios of 90%:10% (L90K10); 70%:30% (L70K30); and 50%:50% (L50K50). The variables of liquid fertilizer observed consist of pH, organic carbon (C), total nitrogen (N), phosphor (P), kalium (K), mangan (Mn), ferrum (Fe), and C/N ratio. Data were analyzed using analysis of variance and any significant differences were further tested using Tukey’s. The results showed that the treatments did not significantly affect (P>0.05) pH, Organic-C, Total-P, K, C/N ratio, Mn, Fe, and the treatments are significantly affect (P>0.05) Total-N.
Keyword: 

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
Keyword: