Judul: Perbandingan metode pengujian kebutuhan oksigen kimiawi dalam air: metode standar AWWA, modifikasi, dan HACH dengan spektrofotometri sinar tampak
Abstrak: Kebutuhan oksigen kimiawi (KOK) merupakan salah satu parameter yang menunjukkan kadar bahan organik dalam menentukan kualitas air. KOK didefinisikan sebagai jumlah oksigen (mg O₂) yang dibutuhkan untuk mengoksidasi bahan organik dalam satu liter contoh air. Metode spektrofotometri sinar tampak merupakan salah satu pilihan metode baku dalam penentuan KOK. Untuk analisis di dalam suatu laboratorium, suatu metode baku perlu dikaji untuk mengetahui kemampuan metode yang bersangkutan. Metode standar AWWA, modifikasi, dan HACH merupakan suatu metode analisis dalam penentuan KOK yang menggunakan teknik spektrofotometri. Perbedaan dari ketiga metode tersebut terletak pada komposisi pereaksi yang digunakan. Oleh karena itu perlu dilakukan analisis KOK terhadap contoh dengan menggunakan ketiga metode analisis tersebut untuk menentukan apakah ketepatan dan ketelitian ketiga metode tersebut berbeda atau tidak. Penelitian ini bertujuan untuk membandingkan analisis KOK konsentrasi tinggi antara tiga metode yaitu standar AWWA, modifikasi, dan HACH. Prinsip dari ketiga metode ini adalah bahan organik dioksidasi oleh oksidator kuat K₂Cr₂O, berlebih dalam keadaan asam dengan menggunakan Ag₂SO₄ sebagai katalis, kemudian direfluks dengan menggunakan alat KOK reaktor pada suhu 150°C selama 2 jam, sisa K2Cr2O, diukur dengan spektrofotometer sinar tampak. Dari penelitian yang telah dilakukan ternyata nilai KOK dari beberapa contoh tidak berbeda nyata walaupun menggunakan metode yang berbeda. Metode standar AWWA, modifikasi, dan HACH dapat menentukan nilai KOK pada kisaran 50-400 mg/L dan memberikan perolehan kembali cukup besar, yaitu lebih dari 95%. Gangguan ion klorida kurang dari 2000 mg/L tidak mempengaruhi nilai KOK dilihat dari hasil perolehan kembali yang berkisar 101,12-101,94%.
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Judul: Pengolahan Limbah Cair Laboratorium Bekas Pengujian Kebutuhan Oksigen Kimiawi (KOK) dengan Metode Presipitasi
Abstrak: Determination of chemical oxygen demand (COD) parameter in water samples produce laboratory waste which are still harmful to be dumped to the environment. It is because COD testing still use several reagents containing heavy metals such as Ag, Cr, and Hg. This research was focused on Hg removal, because of its higher toxicity compared with the two others. The initial COD waste contained 5241.4 mg/L of Hg, whereas the quality standard of Hg according to PP No. 82/2001 is 0.002 mg/L. Precipitation method was studied in this research to treat this COD waste, especially to reduce the Hg content. The precipitation was carried out with hydroxide and carbonate. From several methods tested, 5 of which decreased significant amount of Hg, which were hydroxide precipitation with acid addition (HA), multilevel hydroxide precipitation (HB), carbonate precipitation with addition of hydroxide and acid (KHA), multilevel hydroxide precipitation with acid addition (HBA), and multilevel hydroxide precipitation with addition of salt and acid (HBGA). Those five methods could decrease the Hg content up to 99.96%, into 2.1939, 2.7513, 2.0185, 2.5858, and 2.1683 mg/L, respectively. However these results had not yet fulfilled the quality standard
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Judul: Lejeuneaceae Subfamily Ptychanthoideae (Hepaticae) in  West Java
Abstrak: Subfamily Ptychanthoideae of the family Lejeuneaceae (Hepaticae) in West Java is still poorly known. Publications on this subfamily are out of dated and written in the 19th or early of 20th century. The last taxonomic treatment of Ptychanthoideae of West Java was in 1933, many species names have changed since then. Studies on Ptychanthoideae of West Java are urgently needed. Studies on the Ptychanthoideae were based on the specimens collected from West Java. A total number of 361 of specimens deposited in the Herbarium Bogoriense (BO), Herbarium Biotrop (BIOT), Gottingen Herbarium (GOET) and Bangi Herbarium (UKMB) were examined, those are old and several recent specimens collected in West Java. Recent collections were made from Telaga Warna, Ciater, Gunung Halimun Salak National Park, Cibodas Botanical Garden, Bodogol Education Center and Conservation (Gunung Gede Pangrango National Park), University of Indonesia Campus Depok, including several collections from Banten Province. Twenty four species of Lejeuneaceae subfamily Ptychanthoideae are known from West Java, belonging to 8 genera namely Acrolejeunea (Spruce) Schiffn. (2 species), Archilejeunea (Spruce) Schiffn. (1 species), Lopholejeunea (Spruce) Schiffn. (10 species), Mastigolejeunea (Spruce) Schiffn. (3 species), Ptychanthus Nees (1 species), Schiffneriolejeunea Verd. (1 species), Spruceanthus Verd. (2 species) and Thysananthus Lindenb. (4 species). Two new records of Ptychanthoideae: Mastigolejeunea indica Steph. and Thysananthus minor Verdoorn are reported for Java. A determination key to the species is presented including their descriptions and illustrations.
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