Cleaner production of essential oils from Indian basil, lemongrass and coriander leaves using ultrasonic and ohmic heating pre-treatment systems.

Indian basil (Ocimum basillicum), lemongrass (Cymbopogon flexuosus) and coriander (Coriandrum sativum) leaves are a good source of aromatic oils; however, their extraction volume is low. Hence, two pre-treatment systems (ohmic-heating and ultrasonic) were devised for extraction of essential oils (EO) from the leaves of these three plant spp., which consequently enhanced the EO yield and saved the time and energy. First of all, an experimental set-up was developed for ohmic-heating pre-treatment which was subjected to the optimization of electric conductivity of lemongrass and coriander leaves at 26.25 V/cm and for Indian basil at 22.5 V/cm voltage gradient. An Experimental setup was also developed for ohmic heating-assisted hydro-distillation (OHD). Finally, conventional Clevenger hydro-distillation (CHD), OHD, ultrasonic-assisted conventional hydro-distillation (UACHD) and ultrasonic-assisted ohmic-heating hydro-distillation (UAOHD) methods were evaluated for their effectiveness in the extraction of the EOs. The OHD took 3.5 h time with 410 W power consumption compared to 5 h time and 500 W power consumption in CHD of sleeted leaves. Likewise, a saving of ~ 86% in time and 74% in energy consumption was observed for EO extraction through UAOHD over CHD. Quantity of EOs extracted from all three aromatic plant spp. leaves followed the trend of UAOHD > UACHD > OHD > CHD methods, respectively. Overall, ultrasonic pre-treatment coupled with ohmic-heating assisted hydro-distillation (UAOHD) proved as an innovative and effective clean EO extraction technology which took shorter extraction time and lesser energy consumption with better EO yield over the UACHD, OHD and CHD methods from the leaves of Indian basil, lemongrass and coriander.

Household, hotel and market waste audits for composting in Vietnam and Laos.

In Da Nang and Ha Long, Vietnam and in Vientiane, Laos, there was interest by local authorities in separating and composting waste in order to reduce environmental and health problems at the local landfills and to produce a soil conditioner for local agricultural use. To assist in the planning of composting projects, three studies were carried out to estimate waste quantities and composition. 1. A 9-day audit of waste from 45 vendors in a market in Vientiane, the capital of Laos. The total quantity of waste and the quantity in each of nine categories were estimated for each of six different types of vendors. 2. A 7-day audit of waste disposed by three hotels in the tourist area of Ha Long, Vietnam. Waste quantities were estimated in total, on a per guest basis, and in three main categories: compostables, recyclables and miscellaneous. 3. A 7-day audit of waste collected from 74 households in Da Nang, the fourth largest city in Vietnam. Waste from each household was separated into compostable and non-compostable waste. Over 60% of each waste source comprised compostable waste and this was considered significant enough to warrant further planning of composting operations.