[Investigation of the H2S contamination in cabin causing fishermen's eye burns].

OBJECTIVE: To investigate the H(2)S pollution in cabins which caused the fishermen's eye burns. METHODS: Fifty-six fishing boats' H(2)S concentration was surveyed and 56 fishermen's eyes were inspected. The air samples were collected from 21 fishing boats' cabins, where the eye burns took place and the monitoring conditions met the inspection requirement, in order to confirm the concentration of H(2)S when eye burns and the systemic poisoning happened. Thirty fishing boats were divided into two groups: one was using air ventilating and spraying, the other was using naturally ventilation to find out the effective method of dispersing H(2)S. Five fishing boats were surveyed in which the fishermen had slight symptom of bulbar conjunctiva hyperemia and cough to find out the minimum concentration of H(2)S which caused the eye burns and respiratory mucosa. RESULTS: Among 56 fishermen who were surveyed, 46 fishermen's eyes (92 eyes) burnt and they were from 21 vessels, 10 of them (20 eyes) were moderate, 36 of them (72 eyes) were light. The concentration of H(2)S in the 21 fishing boats' cabins which caused eye burns was (99 ± 38) mg/m(3). The first measuring of the concentration of H(2)S in the 30 fishing boats in which fish were not discharged yet was (219 ± 31) mg/m(3). Air ventilating and spraying group's concentration of H(2)S was (213 ± 24) mg/m(3), while that of naturally ventilation group's was (225 ± 36) mg/m(3). Dispersing after 1 hour, the concentration of H(2)S of air ventilating and spraying group was (21 ± 3) mg/m(3), the decreased concentration was (192 ± 21) mg/m(3), fell 90%; the concentration of naturally ventilation group was (184 ± 36) mg/m(3), the decreased concentration was (41 ± 8) mg/m(3), fell 18%. The difference between the two groups' decreased concentration was significant (t = 25.627, P < 0.05). The threshold value of H(2)S concentration that could cause the eye burns was 38 mg/m(3)(exposure time 120 min). In 7 vessels, the concentration of H(2)S in the cabins was (123 ± 9) mg/m(3) where 10 fishermen's moderate eye burns happened. In other 7 vessels, the concentration of H(2)S in the cabins was (54 ± 7) mg/m(3) where 19 fishermen's light eye burns happened. The difference of H(2)S concentration between the two groups was significant (t = 14.236, P < 0.05). CONCLUSION: High H(2)S concentration and long exposure time in cabin can cause serious eye burns. The bilge air ventilation and inner cabin spraying are the effective method to clear the H(2)S in cabin within short time.

[Pilot study on the biochemical treatment of mother liquid of polyvinyl chloride produced by suspension polymerization].

In the pilot study on the treatment of mother liquid of polyvinyl chloride produced by suspension polymerization (SPVC) by using a novel aerobic treatment system-4 cascade aerobic biofilm reactors with internal circulation, the removal efficiencies of the COD and turbidity at different HRT together with the resistance impact of the system were researched. The laws of the biological growth and the development were observed. Some primary factors (suspended solids, chironomidae larvae, nutrition) influencing the steady operation of the reactor were studied and their controlling methods were suggested. The experiment results show that the start-up period was very short and the total COD removal rate was over 75% at HRT of 14 h, the effluent less than 50 mg/L can steadily meet the requirement of wastewater discharge standard and also be reused after advanced treatment.