Crumb rubber is one of Indonesia’s agroindustry export commodities. This industry faces environmental problems due to their wastes, both liquid and air. The source of air pollution is commonly from drying process that emitted odor from its evaporation and heating phenomena. Industry uses wet scrubber technology as air pollution control from emitted odor from drying process. Preliminary identification in noncontrolled wet scrubber shown that wet scrubber efficiency around 47%. Low efficiency wet scrubbing process causes rain drop of water vapor around drying process. This research used electrochemical based sensor MICS 5524 as ammonia monitoring instrument, assisted with arduino as microcontroller to regulate water discharge through valve controlling scrubbing process. This electrochemical based sensor reads ammonia based on voltage reads by Arduino microcontroller. Ammonia reading then control scrubbing process by adjusting valve opening for spray water distribution. Wet scrubber efficiency increases to 66,96% due to water scrubbing control, also can save water utilization as high as 61,90%, followed by absence of rain drop contains ammonia around drying process area.

The emission from industry has become a significant problem in Indonesia. Usually, the enterprise uses an accredited testing laboratory to conduct emission tests to report its process’s environmental performance. In contrast, this testing was accurate, but it cannot visualize whole time emission from one method. This year, the Covid-19 pandemic also gained some difficulties in environmental evaluation in the industry, including emission performance evaluation. Some big companies may have expensive continuous emission monitoring that can substitute manual laboratory testing. Some other, the small and medium scale industry did not have this system. There is a possible development of an integrated low-cost emission monitoring system in the small-medium scale industry. The low-cost gas sensor rapidly develops and gets more accurate. An engineering scenario of integrating low-cost emission monitoring systems into digital information systems could be developed under some challenges, instrumentation, calibration, and regulative support. By applying this scenario, periodical emission concentration can be evaluated periodically to support air quality management policy.

The coal used as a primary fuel in an Indonesian power plant produces sulfur dioxide emission from its burning process. Several testing and monitoring methods developed, from laboratory analysis, CEMs based instrument, and absorption spectroscopy method developed for this purpose. Differential Optical Absorption Spectroscopy (DOAS) method based on Lambert-Beer law used as emission quantification. DOAS instrumentation developed in this research to measure sulfur dioxide as one of the emission parameters. Sulfur dioxide generated from the reaction between the sulfuric acid and dilute sodium sulfite. CCD spectrometer used to measure sulfur dioxide spectrum intensity at 260 to 350 nm absorption cross-section. There is a high correlation between sulfur dioxide gas produced by that reaction to spectrum intensity, with coefficient determination (r2) 0.9783, 0.9822, 0.9866, 0.9928 or coefficient correlation (r) 0.989, 0.991, 0.993, and 0.996 from lowest range concentration to highest range concentration. Precision analysis from gas calibration standard using Horwitz ratio indicates instrument setup precise enough with 0.504 Horwitz ratio, according to its acceptable range. The suspended particulate matter may interfere with UV penetration into CCD detector in emission simulation test using gasoline generator exhaust that causes 2.5 times deviation error between typical 800 ppm concentrated sulfur dioxide from chemical reaction and gasoline generator exhaust.

This research report new method for ammonia gas concentration measurement using metal oxide sensor-based instrument. Ammonia gas prepared by diluting concentrated liquid ammonia in water collected in container. Ammonia gas then streamed into monitoring path made by acrylic cube. Ammonia gas concentration measured as voltage from MEMS MICS 5524 sensor, then with ESP 8266 based iOT module logged into google sheet. Correlation between voltage and ammonia gas concentration evaluated by linearity test, compare with SNI 19-7117.6-2005 standard method and resulted more than 0,9 liniearity. This measurement totally nondestructive test, it carries no chemical agent could damage environment.

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