Abstract. Rice straw is agricultural waste containing high potency to be treated to biogas. However, the usage of rice straw is still limited due to high lignin content that will cause low biodegradability. The aim of this research was to study the effect of pretreatment using NaOH and acetic acid to biogas production from rice straw. NaOH was varied from 2%w, 4%w, and 6%w; and acetic acid was varied from 0,075 M, 0,15 M dan 0,75 M. The rice straw was cut into 1 cm size and submerged for 30 minutes in NaOH and acetic acid solution. The rice straw then filtered and neutralized before sending to anaerobic digestion process using rumen fluid bacteria. Biogas produced was measured using water displacement method. The result showed that the optimum concentration of NaOH solution was 4%w that resulted in biogas volume of 21,1 ml/gTS. Meanwhile, the optimum concentration of acetic acid pretreatment was 0,075 M that produced biogas volume of 14,5 ml/gTS. These results suggest that pretreatment using NaOH solution is more effective for decreasing the lignin content from rice straw.

Water distribution from water treatment plants may still contain some contaminants such as odour, sediments, discolouration, bacteria, viruses, and worms. This effluent is unhygienic and has potential hazards waterborne disease to human health such as skin disease, itching, influenza, typhus, and diarrhea. These diseases are caused by several contaminant parameters, both physical, chemical, and microbiological. Several methods can be used to treat water such as filtration which can reduce the concentration of contaminants carried or formed in potable water distribution so that it can conform the drinking water quality standards. Filtration has many media types such as activated carbon, greensand manganese, ferolite, polypropylene, yarn, and ceramic. The advantage of activated carbon is low cost, high efficiency, and easy to maintain. Effects of water purification show that the filtration from activated carbon combined with polypropylene filtration processes has significant effects and very effective to reduce physical contaminant. It can reduce 60 – 80 % contaminants, depends on the concentration of the contaminant. This article is a review of some results of the research process.